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by Robert (Bob) Fenner

How Much Sand Underlayment for My Pond?    6/30/13
I am thinking about building a pond.
The pond will be a round, sunken pond, with a 2' wide x 40" long brick edging. The bricks themselves will each be 2" wide and 8" long. The brick will be standard red bricks. They will be laid out vertically. The bricks will be laid 3 deep all the way around the edge of the pond. I calculated I will be using at least 50 bricks in all.
The dimensions for the pond will be:
3.4' L x 3.4' W x 3' D
The pond will be 260 gallons.
The butyl liner I will be using will be 15' L x 15' W
I plan to add 2 inches of extra space for underlayment for the inside of the pond and the edging.
I will be using fine, soft sand for an underlayment.

My questions:
How many pounds of sand would I need for underlayment?
<Likely 300 pounds or so; or you could use carpet (remnants, samples)>
How Many pounds of mortar should I use on the edging?
<Maybe four bags of sixty pounds>
Thank you.
<Welcome. Bob Fenner>

Clay Pond below the water table   10/30/11
<Hiya - Darrel here>
I've pond area which is approx 49' x 3.5'.
<I'm guessing 49 feet in diameter and 3.5 feet deep, right? Because 49 feet long by 3.5 feet wide wouldn't be a pond as much as it would be a moat>
This area will fill with water from the water table and with rain water.
<That's an odd situation. Your water table is very high and/or your rainfall must be substantial.>
In dry spells the water will subside but we have recently dug a well which fills every couple of days from an underground source (probably ground water)
<Probably ground water? Well yeah - unless you sunk your well into a City water main, I'd say it would be ground water>
and this can be used to top up the pond.
Q1: Am I right in thinking that a pond liner would be a waste of time because it would basically float due to the water rising below?
<There is a problem, yes, but it wouldnt necessarily float. All things being equal, if you have an equal amount of water on the upper side of the liner as you have below the liner the liner won't float, it would just not be very heavy. Think of it like this: Why don't concrete swimming pools float out of the water during the rainy season? The answer is because they themselves are filled with water, so the most you have is the weight of the water INSIDE the pool equaling the pressure of the water in the saturated ground. Now if that pool is empty during a flood-like rainy season THEN it will (and they do!) float out of the ground.>
<In your case, if the liner is properly placed, weighted with stonework in strategic places, the most you should have is a FLEX in the pond liner during the rainy season.>
<THAT SAID if your water table really is within 3 feet of the surface of your ground level and you really do have so much rain that it can keep your pond filled, I'd strongly suggest you look into building the edges of your pond UP by a minimum of 6 inches above ground level, if for no other reason than to prevent muddy run-off from entering your pond. A ring of sandbags around the edge, the liner overlapping the bags and then various areas of stonework, plantings, etc. Once I even saw someone ring a pond with sandbags, lay the liner over it, then top it with a ring of sandbags that they then seeded and used as a garden bed.>
Q2. If I am right in Q1 can I use another some sort of geotext material topped with sand or pebbles to prevent weed growth at least on the base of the pond?
The thinking behind Q2 is that the geotext material will allow water to seep in from below but act like a weed control membrane and the pebbles will keep the membrane in place.
<In my experience, all the Geo-text materials available will just turn into dirty, messy mud collectors when used by themselves.>
Or can you recommend another way of dealing with the vegetation that grows in this area.
<I'm going to pass this to Bob for further (read: More Accurate) input><<What you have here is accurate, useful. B>>
Thanks in advance for your help,
Re: Clay Pond below the water table   10/31/11

Hi Darrel.
Sorry about the misunderstanding. Pond is 49' in diam and 3.5' deep.
<I figured as much - I was just joshing you there. We don't get a lot of entertainment down here in the basement of the Flemner building in downtown San Diego chained to your desks so sometimes my mind wanders>
Just to clarify, the pond/hole has a gentle slope down towards it. Thus the difference in height between top of slope and bottom of pond is around 10-12'
<So we have a 10-12 foot slope running down to a flat area that contains our pond? That being the case and rainfall being significant in your area, building a berm around your pond is an imperative. Concrete or cinderblock would be best, but terribly expensive because of how deep a footing would be required. My suggestion is the sand bag approach. It's a lot of work, but not terribly expensive. I'd lay a ring around the perimeter and in the uphill-facing side, I'd drive two 3-foot iron bars (re-bar for construction) through each bag and into the ground - this to help against a sudden rainstorm/runoff wanting to wash your sang bags off the edge and into your pond. Then I'd lay out the pond liner and overlap the bags, then cover the liner edge with rocks, more sand bags, etc. or any way that suits your esthetics.>
However I take your point regarding water weight on top of the liner and the amount of pressure that would exert.
Following on from that, is there a chance that any rotten vegetation might cause gas and produce bubbles.
<Now you sound like you are describing my ex-wife's home-made soups>
I'm guessing if the liner is weighted then this wouldn't be much of a problem?
<Not really, Jim. Unless you're building on a peat bog or reclaimed swamp land, the volume and frequency of gas pockets isn't your problem.>
<Your challenge is countering the volume of water that could conceivably come running down your hillside>
Re: Clay Pond below the water table
Thanks for getting back to me so quickly and much obliged for the advice.
<We're happy to do it - sounds like it's going to be a fun & challenging project>
I understand your circumstances, darkened room, a 1 watt bulb above, head down looking at a screen, never seeing a another soul for hours/days on end. Then there is the mushroomy smell you get in damp basements. I sympathize, I was a software engineer and used to work in similar conditions. Never hearing a voice unless it was 'Oi, Wake up dummy'. Gawd even the smell of wet dog was better than the smell of my underpants after a week stuck in the dungeon. Anyhoot Darrel keep your chin up son and thanks once again for all the advice.
<Jim - before I fell into this gig (literally fell -- Bob dug a hole, covered it with grass and suspended a carrot on a string over top of it) I was a retired software engineer. We had a banner in the coffee room that read: No coffee too cold, no vending machine food too old! <<Wot a hoot!>>
We don't program in C, ADA, Asgol, Lisp, Fortran or any other sissy languages!
We program at the bare metal, in assembler and we don't document any of it!>
<Thanks again for the nice words, Jim. Check out our 'search' bar and search for articles on pumps, drains and circulation patterns.>

clay ponds, Liner const.   9/1/11
We installed a pond at the end of a large patio. We tucked the liner under the last row of pavers and tucked the rest of the liner under the rocks surrounding the pond. Our yard backs up to an area that has poor drainage and as a result of the record rainfall, our liner keeps lifting up due to ground water.
<... You should have in-placed a (French) drain around the basin... either leading away from the pond, or to a sump to pump away...>
The ground under our liner is clay soil and weve read that if you have clay soil, you can build a pond and not use a liner.
<Mmm, rarely advised...>
Rather than fight mother nature, we are thinking of cutting a hole in our liner and letting the ground water seep into our pond. Do you have any thoughts about this? Thanks
<... I would not do this likely... Trouble... w/ water quality chemically and not being able to see into the basin... What are your intentions w/ this pond... I.e., what are you trying to do, grow? IF there's enough extra liner, you might consider raising the current basin's edge by building a footing... raising the berm. Bob Fenner>

Rubber roofing cement quandary    5/29/11
Hello there,
<Hi Gretchen>
Thank you in advance for whatever your answer may be! I have a pond I have been working on for many months. So far so good. I am in the final stages of doing the edging. The pond is a 3,000 gallon rubber liner pond.
Straight sides. I am edging a section with large rock to cover the top of the liner. Water will cover about 4 inches of the rock. I was going to use Rock-to-Rubber
<This: http://www.rocktorubber.com/>
and concrete to hold the rock and ran across a post on your site about plastic concrete. Sounded like a great idea, so I went off to my local home improvement store and explained what I needed and showed photos of the project and expressed concerns about a product which wouldn't harm fish. I came home with Henry HE208R - SBS Rubber Modified Wet Patch Roof Cement.
<Mmm... I wouldn't use this>
I was told it was ready mixed, would dry hard over night and was perfect for the project. Henry makes a product called plastic cement...but I was talked into the rubber cement. Despite my initial reaction on opening the can, I used it anyway. Yep, that's right, I used it anyway. It hasn't dried overnight and after some Googling I have now come to the realization this is not plastic cement or concrete cement cousin at all but an asphalt product.
<Yes... can be toxic, go back into solution if kept wet... and is a mess to apply and worse to remove>
I would ask, "What was I thinking?" but obviously I wasn't thinking, I was just pushing forward with trust in a "professional's recommendation." I've searched for hours to no avail on whether this is a safe product or a huge mistake.
<Our companies used this material for various applications for years... but this was decades back... I would NOT use in a biological setting, nor one where the material is continuously submerged>
My questions are basically, is the rubber roofing cement I used safe? (My gut is telling me no).
<This is NOT a rubber cement, but an asphalt/ous emulsion...>
If not, can I cover it with regular concrete to make it safe or should I replace the liner and start over?
<I'd try covering it over. Bob Fenner>
Thank you for your time!
What was I thinking
North Hollywood California
re: Rubber roofing cement quandary   5/29/11

WOW! Thank you for the amazing less than 5hr fast reply on a holiday weekend.
<Heeee! And what's more, am down in Costa Rica at the moment!>
Yes, I am using <This: http://www.rocktorubber.com/>. Works great. Love it.
<Thank you for this input>
I have a lot of extra liner, so I'm going to take the rocks and extra roofing rubber cement out, cover area with liner and use seam tape to seal off from the pond. Start over just on the edging.
<Mmm, likely better for your "peace of mind">
Thanks again! Amazing "customer service." I've read your site dozens of times and your replies to people have really helped me build a better pond.
All my best!
<Life to you my friend. BobF>
re: Rubber roofing cement quandary   5/31/11

Hellooooo there Bob,
<Howdy Gretch!>
I didn't want to re-disturb your Costa Rica adventure but now that it's Tuesday...
<Am just back, blurry>
My partner's response to your quick reply while in a foreign land was, "Shut Up! Who is this guy?" She's a hard one to impress, too :o) We both thank you.
The rocks are out and individually sealed in small trash bags and the excess asphalt had been scraped away into a sealed container.
<What a mess eh?!>
It's like a Superfund Site in my own front yard! You weren't kidding when you said that goo is a mess to clean up!
<Oh yes>
I'm off work Thursday and plan on tackling the edging again. Just so I don't meander off on another ridiculous path of mistakery, what's the mixing ratio for plastic cement, pea gravel and sharp sand?
<Gravel/aggregate two-three parts, sand two and cement one... practice w/ the water ratio so as not to be "too loose" (Lautrec?)>
I hope you are well rested and suntanned not sunburned!
<After many years in the dive-adventure/underwater natural history and petfish biz, am rarely "out in the sun", esp. in the tropics. Thank you though, BobF>

50 year old concrete goldfish and Koi pond -new drain question 11/5/10
Thank you for such an informative website. I have read most of the information and have a somewhat unique situation. I've lived in my home in Oregon 32 years. The 600-gallon concrete pond was here when I moved in. The pond is 14 feet long, semi-kidney shaped, and is only appx. one foot deep (below grade).
<Too shallow to be of functional use as a biological system>
(Don't choke - I have six large healthy Koi and some goldfish for many many years in this shallow space!) There is a crack crossways in> the middle. Over the last 32 years I have patched the crack every few years with various methods including 2-part resin or hydraulic patch. I have now patched the crack again with hydraulic patch. And now, after all these years, I want to make the pond deeper by building forms and pouring an 8" thick concrete wall above ground, 18" high, and tying it in with the existing concrete pond's lip with rebar and also digging out from underneath the lip so the concrete pours under and around - incorporating the lip for more of a solid footing - and then cover all with an epdm liner.
<I'd put the/this liner under the concrete (and wire mesh)>
I have received a bid for this construction and am close to accepting it but am doing final research and preparation for the "details". The existing 50-year-old concrete pond has a one inch i.d. iron pipe drain (that I've always kept corked) which is appx. four inches below the rest of the bottom of the pond. I would really like to take advantage of this lower area by cutting another hole (removing the 1" pipe) and inserting a 2" pvc drain pipe that will lead to a buried settling chamber (same depth and height of the pond) from which water would be pumped by way of a submersible pump which is suspended appx. 1/3 down from the top of the chamber. Water pumped out of the chamber will go to an upflow biofilter, then overflow back to the pond. No waterfall (at least not now). Though I would love to have this 2" drain, I am also very scared of it leaking. The drainpipe will go through an epdm liner, underlayment, concrete, and then into the settling chamber. What is the most secure method to attempt this retrofit with the liner and concrete that guarantees that it will never ever leak?
<To lay the liner down over the existing basin AND the new upper wall... run reinforcing mesh over this... mortar over this... and for the pipe, to cut slots and an X over it, drape the EPDM over the pipe, Panduit and band-clamp the liner over the pipe, and pour a good 3-4 inches of mortar around and over this area. Solvents won't work here>
Or should I, for anxiety's sake, forget the drain and simply pump out of the pond as I have done for 32 years?
<Up to you; I would have a drain myself>
I also want to have a floating skimmer to catch leaves before they settle.
Up until now I have never had a skimmer. Leaves and debris sit and rot on the bottom of the pond. Perhaps simply having a skimmer would be adequate for the purpose of trapping a majority of the debris, thus eliminating the need for a bottom drain and settling chamber? It is a dilemma for me, and I am not good at choices like this!
Thanks ever so much for any help you can offer.
Shirley in the Pacific Northwest
<BobF in N. Viti Levu, Fiji>
50 year old concrete goldfish and Koi pond -new drain question
Dear Bob,
Thank you very much for your reply and comments. I would like to clarify one thing if I could:
<Let's see>
Your statement "To lay the liner down over the existing basin AND the new upper wall... run reinforcing mesh over this... mortar over this..."
To recap - I have an existing shallow concrete pond. I am going to build the sides up an additional 18" with concrete. I will end up with a concrete pond, 12" underground and 18" above ground, equaling 28" deep, all one (semi-smooth) surface inside. Are you meaning to then put mesh on the entire inside (over the old and new concrete) and then put a layer of mortar over all of it?
<Yes, w/ the liner underneath>
Does the epdm liner sit on the mortar better than it would laying on the concrete surface?
<... Read here: http://wetwebmedia.com/PondSubWebIndex/linerspdconst.htm
and the linked files above>
What is the purpose or advantage of the mortar?
And, I forgot to mention, I plan on having at least one layer of commercial pond underlayment or equivalent so the epdm liner will not come into direct contact with the concrete.
I decided not to do a "normal" bottom drain, but I came up with another option that I've been passing around the online pond community for feedback.
I attached a diagram (I tried just pasting it onto this page but it wouldn't work - I hope you can open the document).
<I don't see it attached here>
The only thing different I'll probably be doing is not having the skimmer tied into the same pump as the drain - I'll be putting it on a separate line and pump. Anyway, the pond and settling tank equalize water levels by way of the upside-down "U" 'drain' pipe, similar to if the drain was on the bottom and gravity fed. I figure a little extra pull would be enough to pull up the fish waste.
<Better by far to have a "settling basin" tied into this deepest drain area... NOT to pull water for recirculation from here... See WWM re pond plumbing...>
I know this is unconventional. I will experiment with it and different setups until I get something that works.
Thank you again for your feedback from Fiji!
Shirley in Oregon
<Bula! BobF>
Oh, I do see/find your graphic and I do totally agree w/ the concepts presented. Thank you for sending it/this along. B

Re: 50 year old concrete goldfish and Koi pond -new drain question 11/6/10
Oh, OK. My mind was blocking what you had written, and now I remember reading this (mesh and mortar over epdm liner) on WWM.
<Ah, yes; SOP, standard operating procedure for the majority of basins we installed>
I spent a few hours
one evening reading everything on the website (and two other sites),
<Easy (for me at least) to become confused w/ so much, disparate intake>
but that was a couple weeks ago and my mind is now waterlogged.
<Heee! Mine as well; from diving so much this past week, too much in the way of fab meals...>
At this time, I will probably just have the liner for ease of installation and time constraints. I can always come back and do the mesh and mortar coat later if I want. And thank you very much for your encouraging words about the diagram and plans of my contraption.
<An excellent symbolic representation of what a generalized plumbing scheme
should be for biological ponds>
I am fairly confident about the overall concept, and it can all be adjusted where needed; my only crucial decision right now, before the wall is poured, is what size pipe to put through the wall (at the old pond level). It needs to be large enough so that when I install the inner and outer pvc extensions, I won't be saying "I wish I would have made the pipe in the wall larger..." I can always scale down to the "pull-drain", which I had decided upon 2" but now I am tending toward 2.5", keeping in mind that the smaller the diameter is, the more pull?
<In practical terms, not so much of import; 2- 2 1/2 will do fine for the gallons involved and equi-level draw, pump applied>
Of course, depending upon what gph pump I get. It's all experimental since it's a unique setup. I only have my 500 gph PondMaster Mag-drive submersible/external pump that I've used for 18 years, and a 640 gph Little Giant (not mag. drv.) submersible/external pump that I picked up at a yard sale for $5 - thought I could use it somewhere outside, maybe for the skimmer.
<Mmm, this pump won't likely "drive" such>
Anyway, I know I will need to purchase a new pump and getting all of this planned out and then actually buying something is daunting. I am tending towards a PondMaster 1800 gph (3/4" outlet) or 2400 gph (1" outlet)
Mag-drive for the settling tank and I can scale down the outflow if needed.
<Mmm, a remark I should make re your checking the amperage draw, likely cost of continual operation>
I might need to split the outflow so that the water in the bio-filter tank isn't rushing through so fast that it doesn't have a chance to do it's bio thing???
<Mmm, not likely a real concern here either>
I've read about dwell times and that's one more thing I'm trying to mix into all of this. Too many things to think about! I'm trying to learn as much as I can before I get my feet wet.
Thank you again for your quick responses and information. If I didn't have the internet with which to study, learn, and correspond, I would be up a creek! Ah, too many water jokes!
Shirley in Oregon (~_~)
<You're doing, ah, swimmingly. BobF>

Re: 50 year old concrete goldfish and Koi pond - further adventures  11/11/10
Good morning, Bob.
<Morrow Shirl!>
Well, my plans have changed somewhat, though not in the grand scheme of things. Yesterday my (very tolerant and polite) contractor began excavating (I like that word - sounds like something is finally happening!) around the old pond's edge in preparation for the forms for the new 8" wide x 18" high wall. He will be drilling into the old pond edge to affix rebar vertically, and rebar will also be cross tied horizontally around the perimeter. A 2" and a 1" PVC flow-through pipe are at the existing pond's level (at bottom of new wall), and a 1" overflow pipe at the top. Ok, so what has changed, you ask? The only part I never felt comfortable about with this whole installation is the liner. I know, it's wise and final and safe. Call me crazy, but, after having my concrete pond for 32 years, I just don't like liners unless absolutely necessary. Soooo, no liner for the time being.
The old pond is patched and could be used as-is for a few years, so I'm not worried about that at present. After the new concrete is poured on top of the old edge, I will probably put a wide bead of hydraulic patch around the seam to seal it,
<I do hope this works for you. Such "cold seams" rarely do... in weeks, months, they crack>
and around the pipes, unless I use something like WaterPlug?
<A good choice. This or other expansive patch>
The new concrete is the question. I am having acrylic added to the mix for stability as well as, I am thinking, for slight waterproofing and to reduce leaching?
<Yes... all good properties... do utilize "plastic" cement as well>
I will wash the new surface either with muriatic acid or vinegar a couple times and rinsing.
<Dilute the first by about ten times... take care not to breath in the fumes of this 3 molar Hydrochloric Acid>
I am pondering the use of Thoroseal (or equivalent), but haven't decided, yet, and haven't looked locally to see what's available.
<Can be ordered or similar found/substituted>
I know concrete is porous, but how much could/would it actually leak through an 8" wall?
<You may find out>
My old pond is 3"-4" concrete with no waterproofing sealer. And, of course, whether I waterproof or not, there's the leaching business - which, as I said, I'll be prepping with the acid or vinegar. When I am to the point of adding water for the fish, rather than fill the pond to the top, thus exposing the entire surface of the new concrete sides to the water/fish, I am considering keeping the water at the old pond's level, and then allow it to slowly creep up the side (actually, Oregon rain will do this) a little at a time over the next few months. This would give the new concrete time to cure and gently leach throughout the coming wet winter. One question is, how much will concrete leach alkalinity if it's not actually standing in water but water is just dripping down the sides?
<Slower, but... again, the plastic cement is far less caustic>
I would be testing Ph regularly and doing water exchanges when needed. One thing I will say - if this doesn't work and I end up with a 32" deep pond next spring that won't hold water above a one-foot depth, I can, and will, put a liner in at that time. But I feel a lot more comfortable at least giving it a try, first, without the liner.
So, am I crazy?
<Well, not w/ this project at least. Or, perhaps we both are>
Yea, probably. If I didn't have the old 600 gallon pond that I know and trust to get me through the winter, I would never consider this.
Your thoughts?
That's the news in Turner, Oregon.
Hope you're having a marvelous time!
<Thank you! BobF>
Re: 50 year old concrete goldfish and Koi pond - further adventures  11/11/10
Thanks, Bob, for your input. I guess I thought acrylic was what was added to make plastic cement.
<Mmm, no. See the Net re Plastic Cement/s... easier flow, lower alkalinity...>
I'll talk to the contractor about it - I want to maximize my success any way I can up front. I also wanted to find out if there was a particular product I could paint/spray/brush on the old pond edge to increase and insure better adhesion with the newly poured concrete.
<Mmm... there are some... look like "white glue"... but these (again) rarely work. The idea of the foundation coating after is good>
One thing I will mention, the contractor has back-dug out underneath the edge several inches so that, when the new wall is built, the concrete will be beneath and completely incorporating the old pond's lip.
Thanks again. Shirley
<As many welcomes. B>
Re: 50 year old concrete goldfish and Koi pond - further adventures 11/16/10

I found the Plastic Concrete online at Lowe's, so I know what it looks like, except it's not available in store anywhere near my home, nor is it at Home Depot. Bummer. Down to the last wire now - the forms are up and they pour concrete tomorrow morning.....
<... And the folks doing the concrete work can't source it? Strange. B>

Re: 50 year old concrete goldfish and Koi pond - further adventures   11/21/10
Well, Bob, things are hunky dory here in Oregon.
<Up for me, and shades of David Bowie album titles!>
I now have the Great Wall of Turner in my backyard!
It looked imposing, at first, but I'm getting used to it. It makes my former one-foot-deep 600-gallon pond look huge.
<Mmm, isn't it actually the other way round?>
The newly poured wall ended up being at least 20" above ground level, and anywhere from 8" to 11" wide. The top lip of the old pond was ground down to get a good clean surface, and a bonding agent painted on for better adhesion with the new concrete. The pouring was done four days ago. Yesterday I cleaned out the pond from leaves (which I left in to act as a barrier to concrete "splops"), debris, gravel, and stuff. I cleaned around the "seam" between the old and new. I did some checking - the WaterPlug that you recommend is another brand name for the hydraulic concrete patch that I've used for 28 years. I will be applying this all around the seam, as well as around the pvc drain pipes that were poured in place. And then I will use Thoroseal. I am tending towards the regular Thoroseal Waterproof Coating, not the TS Foundation Coating. Partly because the application directions sound a little more user friendly, and also because only it is approved by the NSF for potable water. I am somewhat mixed about whether I'll use the Acryl-60 additive.
<I've used it and not... Don't know that it makes a great deal of difference in these applications>
I have read some postings that claim that it prevents the TS from soaking into the concrete properly, and that it can cause the coating to crack. This might be as a result of not following directions... I've read all application instructions a few times and will read a couple more times before I make my choice. Any comments or preferences you might have.....
First question: How long should one wait before applying Thoroseal to newly poured concrete?
<A few days>
Does the concrete need to "cure" for a week or two?
<Not this long>
The temperature here has dropped to 32º last night and TS shouldn't be used in temps under 40º, so I can't do it immediately, anyway. But I just wanted to check.
Second question: Since I am using Thoroseal, is there any reason to acid wash (I would just use vinegar solution) the concrete before the TS is applied?
<Not IMO/E>
I will be acid-washing the TS after it is cured.
<Good... mild only... diluted as stated before... mopped on (wear olde clothes that cover your arms, legs...)>
Third question: Is it advisable to Thoroseal the outside of the concrete wall?
<Can... more for looks, conformity>
I'll keep you posted on progress. I was thinking that I wouldn't completely fill the pond immediately after TS'ing and simply allowing rain to fill it throughout the winter season, but I might go ahead and fill it sooner so that I can get my settling tank installed to see if my "semi-gravity-drain" invention will work.
That's the news from Turner, Oregon. Hope you are doing well.
<Thank you... Out to see the new Potter flick in a bit. BobF>

Liner install 10/20/10
I have a brick enclosure. It was probably originally for flowers. It's about 3 feet side and about 10 feet long. The enclosure has the brick wall of the house on two sides and a 20" wall on the other two sides (at least double layer of brick). At some point some of the dirt was removed and a small water garden
installed. I want to excavate all the dirt from the area and line the enclosure with pond liner, and put a small water fall at one end of the enclosure.
This is to house a couple fish along with continuing to have some water plants.
<I see>
I have two questions/issues:
1. What is best to do for the liner that will be on the house side?
<To "trap" the upper edge between the current top and a new cap; barring this, a very messy process of fitting (don't cut all the way to the top till it's test-filled w/ water... using a "glue" of some sort (usually
asphaltous in nature... the messy part), the liner to the vertical walls...
This is covered in the FAQs archived on WWM under liner use on the Pond Subweb of WWM>
The vertical wall will have no place to overhang and cover the liner.
<Understood... the liner has to terminate/end higher, above the water level line>
The outside walls, the liner can overlap the wall and will have a course of 4" cap stones setting atop the liner.
<Ah good. This is best>
I was thinking I might have to put another layer of 4x4's or brick alongside the house brick higher than the pond waterline, then use a final row of brick/stone to set atop the liner. I was not going to mortar the bricks (or 4x4's) as they will be held in place between the house exterior wall and the water pressure.
<I would eventually mortar in... looks nicer and there's less chance of the rock/cap falling in, tearing the liner. There are colours/dyes you can add to the mortar mix>
2. The existing power outlet would actually be below water line, so I must relocate the box. This will involve running a bit of conduit from the existing outlet box up to the new location. I would seal the hole where the conduit enters the house. Is it a bad idea to have the electrical conduit coming out there and having the liner over the conduit.
<Can be... You might want to look into installing a junction box... in the basin, or a compression coupler to waterproof fit the electrical cable. In all cases, the line MUST be fitted w/, through a GFCI circuit>
I think so. My alternative is to build a wall to pull the pond keep the pond away from the conduit and
relocated outlet box. I'm thinking I'd just use 4x4's to build that up.
<Mmm, do read on WWM, elsewhere re>
Any suggestions would be appreciated.
<Bob Fenner>

Re Liner install - 10/22/10
<Brion, you did get my response?>t;
I'd sent a message about the liner install. I thought I'd show send a few photos to see if a picture helped. <Mmm, yes>
"Site-1-Small" is a ground level view of the site. The rubble around the wall is the rocks, broken tiles, broken bricks that I excavated from the enclosure.
I probably need to clear those away before my wife loses patience with the project (the budget's already exceeded)...
<You are wise here>
The majority of the outer wall will be the upper ledge where the liner will terminate. There is one of the
stone blocks that will set atop the liner one all is in place.
<So, I understand that you'll be breaking off the remaining/shown cap, capturing the liner edge under this area on the two exposed sides>
TopRight-Small" shows the window/outlet box. I intend on putting a junction box and conduit around to relocate the box.
<Good... Needs to be six feet away from the water, have a service switch, be wired through a GFI... according to the olde NEC at least>r /> But, it turns out the box is probably the limit of where I should go. Just below the outlet box you
will notice a black pipe. That is the drain pipe from our kitchen sink that goes around the outside of the house to connect with the sewer. I probably don't want to cover that up with the pond. So, my thought is to run a concrete block course between the house and the outer wall. I'll also need to form a repository to hide my Laguna power-flo 1400.
<Mmm, a wooden "box" will likely be best... Above grade; with all set upon a pad... concrete cast or pre-cast...>r /> Backfill and possible devise some waterfall feature. I'll put some concrete footer down before the blocks.
Then possibly a cap block course. I'll then be able to put stone blocks atop the liner there.
WallRight-Small" shows another view of the outlet box. The liner should come up just to the mortar joint above the top of the outlet box. The outside wall is about 1/2" higher than that mortar joint. I'd wanted to go all the way to the other wall, but don't think I should cover the drain line. And, I did need a space to house the filter.
TopLeft-Small" shows where the largest part of the pond will be. Note along the house wall there is no ledge for the liner.
<Yes... unless you build a wall/ledge to mount same over... you'll have to "stick" the liner up there... not easily done as previously I wrote you>r /> Also, you may notice that I excavated a bit below the footers for the wall. I'd pulled out some clay drain
tiles. I don't know if the weight of the water could collapse those.
<I would definitely put something there, compact it...>
Length-Small" is one other view. It's a little over 8 feet from the nearest wall to the outlet box.
This gets to my core puzzle. What would be your recommendation for house wall side of the liner. I think the two core options are 1) adhesive the liner to the house (don't like this). 2) build a wall against the house (4" maybe) that will then provide a ledge for the liner.
What is the preferred material. Brick would match the rest I suppose, but what about treated wood 4x4's?
<Not wood... Brick, block will be fine>
Also, what do you recommend regarding filling up the excavated portion to the wall footers(e.g. concrete, gravel, sand, dirt)?
<Concrete would be best... floated to a given/made deeper area... depression... to facilitate draining, solids, "bad" water removal>
I need to cover some of those sharp edges. I've been searching the site, but a link to any FAQ/article would be appreciated. I do have underlayment to use and might have enough to double it.
<I'd float the bottom out in concrete w/ small aggregate (nom. 3/8" or pea gravel)>
I've got two 14" Koi in a 40 gallon holding tank. I'm sure they're anxious to get to their new digs...
<Ah yes>
Brion Jones
<Welcome. BobF>

Attaching Firestone liner to Waterfall Filter  4/14/10
I am replacing an old waterfall liner which was installed really badly (by me) and has developed new leaks every spring. I have finally had enough and am planning to redo the whole thing. One problem I'm having is the proper way to attach the liner to the underside of the waterfall
filter/spout. What kind of glue/tape, etc. should I use to attach Rubber liner to the filter. I think I used double-sided tape the first time and it did not hold. This has been the source of my latest leak.
Thanks, Lou
<Mmm, this may sound a bit whacky/whacked, but I have used and suggest you consider using a "water proof" roofing "tar" product... IS tremendously messy to apply... but is the best available, most appropriate technology...
See your hardware stores re Henry's, Marvin's... product lines. Wear olde clothing, gloves... have rags, a solvent on hand for clean up... take your time, pre-cut the liner to fit... I'll be thinking of you...
Bob Fenner>
Re: Attaching Firestone liner to Waterfall Filter  4/14/10

Thanks Bob-
Is this type of "stuff" toxic?
<It is not, once cured>
I have fish in the pond. Can I use the rubberized roofing caulk available at the home improvement store in the pond or is it toxic?
<I think this material is okay as well, but I would contact the manufacturer re ahead of use>
Don't want to kill the fish in this process.
<Understood. BobF>

Pond liner adhesion to vertical natural rock.  3/11/10
I have a vertical rock 15' high with a pump that pipes water to the top and spills it over the edge to a small pond at the base. I want to install Pond Liner up the face of the rock and use it to keep falling water from disappearing. I noticed you told someone they could simply use roofing tar to hold the liner in place but am wondering if it will work on a vertical rock?
<Yes... a mess to apply... and the area where the liner and rock is exposed needs to be coated over in turn... With something waterproof, to preclude the "tar" from being wetted. Mortar... quick set type... with glue... and colour... works well here>
I have been considering cutting the rock and poking the edge of the liner in the gap and know I will need to seal the liner at that point.
Was considering drilling holes in the rock and installing pegs to hold the liner up. The distance from bottom of pond to where I would make the cut up the face of the rock is about 2 feet.
Thank you so much for responding. Misc pics Spokane 002.jpg
<Do wear gloves, clothes you won't mind tossing... have a solvent (maybe even just gasoline) on hand to clean up... Bob Fenner>

Rectangular indoor Pond with viewing glass  11/14/09
I am considering making an indoor pond of size 16' long x 4' wide x 30 inches tall. It is going to be rectangular in shape with an open top.
The container will be built out of 2 x 4, 4 x 4, and 3/4 inch plywood.
In the front of the pond, will be two 7 ft x 2 ft long viewing glass 3/4" inch thick.
I have seen these DYI project done with epoxy paint and or fiberglass.
<Mmm, our businesses put in a few of these viewing panels. We had "races" built... "L" flanges on two sides (inside and out, bolt the liner twixt with caulking)... enclose the glass on the water side>
I was exploring the use of the EPDM 45 mil pond liner to do the project.
The two areas I have concern with are
1) Best way to seal the vertical corners
<Silastic, after the metal construct has been installed water-tight>
2) Best way to cutout the viewing area and sealing it to the glass or siliconing it to the glass/wood for a seal.
<Build the race in place, "pinching" the liner twixt the race faces... Silastic the glass in the water side>
I am considering buying a 10' by 20 ' piece of the EPDM pond liner.
Cutting a pattern like this
16 ft

| 30 "
| 30"
| 4 ft
| B
| Front Panel to have two
| A
| 7 foot openings for viewing
| glass


Any suggestions on how to seam all the Sides A to Sides B to form a corner.
<You'll need a bigger piece of liner than this... needs to go up, above water level, attach to something. See WWM for some S.O.P. input>
Suggestions on how to seal the 7 foot openings.
I think I have a pretty good design for the support container but was wondering about whether I can do this with pond liner
<Well... I would make the area/wall for the viewing panel out of cinder block, fill all cells... and use wire mesh on the inside of the liner if you intend (and I would definitely) shot-crete, otherwise concrete the inside of the basin. Bob Fenner>

Pond Liner 9/22/09
Hi We would like to make our pond bigger and I was wondering if it was safe to seem two liners together maybe the seem would be 15-20 feet long? What do you think. Thanks Lisa
<Yes... liners can be seamed together... Some are annealed (solvented) like PVC... Others require adding an intermediate material for physically "band-aiding" the liners together (Rubber et al. liners). See the Net, WWM for details. Bob Fenner>

Does algaecide and chlorine cause damage to pond liner?  9/6/09
Hi, I'm a new pond enthusiast and have successfully put new life in our pond that was falling apart. We don't have and may be won't have fish and are still in the process of deciding which water plants to keep. In the
mean time, I've been using algaecide in which the active ingredient (60%) is
Poly[oxyethylene(dimethyliminio)ethylene (dimethyliminio)ethylene dichloride. FYI... I use this same algaecide for my swimming pool.
I really want to know if this type of algaecide will damage the pond liner (45 mil rubber liner).
<Not as far as I'm aware. Butyl/Rubber liners are quite chemically unreactive... and any material "lying" on the liner could be easily rinsed, washed off>
I have also been putting chlorine in my pond. This is same stuff that I've using for my swimming pool. Does that damage the pond liner?
<This might... hypochlorite is a strong oxidizer... I would take care not to use too much (less than 1 ppm free Cl), nor use in water with a low pH (under 6.0)>
Thanks in advance.
- Hiren
<Welcome. Bob Fenner>

Natural pond to waterfall transition construction? 6/17/09
I am planning to construct a waterfall from a manmade (branch fed) non-liner pond over an earthen dam and would appreciate how to make the transition from the pond into the waterfall trough. Currently the pond which is approximately 25' long 15' wide and 6' deep at the center, drains through an 8" PVC pipe installed vertically and elbows under the dam to drain into the existing stream bed.
<A good idea to "sleeve" this overflow... to direct water and solids from the bottom of the water column... cut some notches in the larger diameter pipe's bottom... and slip it over the 8", a couple inches higher in height...>
This keeps the water level from overflowing the earthen dam.
I intend on constructing a concrete trough, roughly 3' wide and 12" deep over the top of the dam and using a liner underneath and down the waterfall path. The top of the dam is about 6' across before the fall starts of about 20 feet in length at an angle of approximately 45 degrees back into the existing small stream bed. My concern is where the pond meets the trough.
I was told not to extend the waterfall liner into the pond since water will be able to leak under the liner,
<This is so... capillation will/would work here to weaken the earthen dam...>
so I plan to start the liner about 3' back (under the concrete) from where the pond meets the mouth of the trough.
I intend on using plastic cement with wire grid or rebar to cover the trough and waterfall.
<With the water level lowered...>
I am unsure on how to construct the "mouth" of the trough.
<And I am hesitant to encourage your doing so w/o more substantive information>
Any suggestions on how to form the mouth of the trough to prevent leakage or erosion under the cement would be greatly appreciated.
Also I will extend the 8" PVC pipe to just above the water level to act as an overflow during heavy rains since this small creek can turn into a small torrent at times.
<A very good idea... I would have two such egresses, both sleeved>
Appreciate your suggestions.
<Do understand my alacrity here... and direction in encouraging you to have a soils engineering firm up to review your situation in detail. At the worst, what might be the consequence of the earthen dam giving way all at once? Are there weir dams distal? I would be very hesitant to modify the existing berm myself. Bob Fenner> 
Re: Natural pond to waterfall transition construction? 6/18/09

"<Do understand my alacrity here... and direction in encouraging you to have a soils engineering firm up to review your situation in detail. At the worst, what might be the consequence of the earthen dam giving way all at once? Are there weir dams distal? I would be very hesitant to modify the existing berm myself. Bob Fenner>"
Thanks for the reply Bob. The berm has been in place for about 3 years with no problems having the water drain through the PVC pipe. Just want to install a waterfall over the top for aesthetic reasons. Am a little confused about your question "Are there weir dams distal?" not sure what that is.
Can you elaborate on that?
<Yes, gladly. Am inquiring re mechanisms that might prevent damage further downstream, one such are weir dams... See the Wiki coverage here... IF you were to build such an overflow/fall, I would only do so with emplacing concrete buttresses beyond the "edges", sides of the present dam... My fear is that anything less could become unstable with the wetting of soil that will occur with the liner emplacement. BobF>
Thanks again,
Re: Natural pond to waterfall transition construction? 6/18/09

Certainly appreciate your input, thanks again for taking the time to respond so promptly.
<Happy to be of assistance Alan... I do wish we could do summat of the equivalent of a "distal Vulcan mind-meld"... so that I might more fully understand the project there. Again, as it's likely abundantly obvious, I shy on the side of ultra-conservancy when it comes to matters of potential great harm. Best, BobF>

pond construction, shape... liner use 6/6/09
I'm building a raised formal geometric shaped koi pond.
<Mmm, beware of "tight corners"... for your fishes (Nishikigoi "panic" at times when "caught in corners), as well as circulation and all it entails reasons>
Concrete block walls with sand/cement hard bottom and liner. Questions;
#1....in regards to the liner, is it possible to cut it into sections, align them (with overlap) and "weld" or bond them together to make a form-fitted liner in order to avoid unsightly wrinkles and folds?
<Yes it is possible. Do be sure to check re the type of material/solvent
for welding (we used tetra hydro furane for PVC for instance)>
I'm a fairly "handy" guy and I'm not afraid to try anything at least once!
#2.... I plan to install a VERY heavy cast concrete statue (fountain) in the middle of the pond, with its base just below water level, resting on an "island" of concrete blocks (4 ft pond depth). My thoughts are these;
poured concrete footer, an underlayment, liner,
<Mmm, the underlayment first... perhaps a piece of carpet... then the concrete...>
then concrete block "island" mortared above, and of course the statue on top. Obviously an enormous amount of weight. Any advice here? Thank you in advance.
<Enjoy the process. Bob Fenner>

Underlayment alternative???   5/17/09
Hi Bob, first of, great site. Thanks very much for all the insightful info.
<Welcome Robb>
Now to my underlayment question, I have a small surplus of very thin (1/4 inch Styrofoam sheeting I was thinking of using for the underlayment base of my pond. Do you see anything that would be unadvisable before doing this?
<Mmm, no... other than the Styro will compress, perhaps allowing something sharp to penetrate? If you don't have such sticks, stones underneath/twixt, I'd not worry re though>
Thanks for your insight!
Best, Robb
<And you, Bob Fenner>
Re: Underlayment alternative??? 09/19/09

Thanks Bob, I will send you a picture when I get it all done. I am pretty happy with the results so far.
<Ahh, thank you Robb. BobF>

Pond liner toxic?  7/7/08 Hi, I recently purchased a 45mil EPDM "fish friendly" pond liner from the Pond Depot (Ponddepot.com) for a 4000 gallon pond and set it up. So far, my fish keep dying on me (3 to 4 Koi and goldfish at a time to see if they survive). It takes 3 or 4 days, but they all eventually die. The pond is 4 feet deep for about half of it, but has high sun exposure and has been up and running for about a month. <... is this system cycled? How filtered... oh, I see this below> I am using a high powered filter and pump by Tetra and have put plenty of dechlorinator, etc. in the water. I have an identical pond that's 4 years old and supports fish just fine. It has the same filter, pump, maximum depth, and sun exposure, only it's 2000 gallons deep and uses firestone's 45 mil EPDM pond liner. My question is if my liner is "toxic" despite its label as being fish friendly. How would I test something like that? <Mmm, a bioassay likely... as you are actually doing> Pond Depot says it's fish friendly, but I'm at a loss here. This is a real chore (and very expensive) to just "switch to a new liner", there must be some way of knowing if it's toxic. <EPDM is non-toxic... Something else is at play here... I would dump the water out, re-fill with water from the old/established system, wait a month, allow this system to stabilize, and try some fish from a known-healthy source. Bob Fenner>

Re: pond liner toxic? Bob, thank you for your prompt response to my concerns. I feel better about the liner (dreaded the thought messing with that) and will continue to try and make this pond a success. -Martin <Thank you Martin. Do please relate to us later how this turns out. Bob Fenner>

Re: pond liner toxic? -update 8/16/08 Bob. You were right, it wasn't the liner. Something toxic had most likely gotten into the pond the first time. After draining it and starting over, I have a functioning pond! Thanks again. <Ah, thank you for this update. There are a few principal ways contamination can get into ponds... run-off, sprays and fertilizers from surrounding landscape... Even "bug sprays" from not very close... I remember times when folks would call our service co. in a tizzy asking what was going on with their pond fish... I'd tell them "lick your finger and stick it in the air"... and walk/run in the direction of the incoming wind... Extermination co.s... Bob Fenner>

How to Affix Pebbles to Sides of Rigid Plastic Liner 04/22/08 Hello, Crew: <Angie> We have a rigid pond liner from Lowe's - kidney shaped, approximately 6' x 3'. After sustaining a bullet hole last summer, midway down, the pond developed a leak. <I'll bet!> We removed the pond and treated the outside with a gallon of asphalt roofing sealant, paying special attention to the hole. <Mmm, won't "do it"> On the inside, we would like to affix pebbles from the lip down to the plant shelf in the hopes that this will offer a more natural look on the sides when the water level is low due to evaporation, etc. I have been told not to use the roofing asphalt as "grout" due to fish toxicity. We plan on having only a few goldfish and water plants. Is there another inexpensive product that will adhere the pea pebbles to the rigid plastic? Cost is a major factor. Thank you very much for your expertise, A. <I'd look about (maybe Pier 1 Imports) for some of the "already affixed" material that I've seen sold as "place mats"... Last time was in Laguna Beach, CA (last week) at a gift shop... and cut and hang this material that already has these "wampum stones" affixed (I think with "glue gun" material or some sort of serious epoxy. Otherwise, you can try affixing them yourself... with the liner up, out, laid out and dried... with 100% Clear Silastic... will take a while to set, cure... Bob Fenner>

Pond liner exposure to winter weather 10/14/07 We drain our 4000 gallon pond and would like to leave it empty for the winter. We want to leave it empty and then clean and refill it in the spring. All fish and plants have been relocated to another pond. Will this cause any damage to the pond liner since it will be exposed to cold central Illinois weather? <Mmm, likely not IF this liner is of butyl/rubber... EPDM or composite make-up of adequate thickness (30 mils or more let's say)... I might throw some straw on it to prevent some possible damage by accrued snow, water/ice. Bob Fenner>

Pond question - 8/17/07 Mr. Fenner- <Mr. Agins> I recently installed a pond with approximate nominal dimensions of 13'L x 16'W x 2.5' D. Because of the rounded corners, and such, it is less than the 3900 gallons the dimensions would imply, perhaps by 20%. So, let's say that it's roughly 3000 gallons. The pond is EPDM lined with EasyPro aquafalls at the head, and skimmer on the wall opposite the waterfall. The waterfall feeds a stream approximately 3'W x 10'L x 9"D. I am using a PondMaster 5000 GPH mag drive pump. <Okay...> When I first assembled everything, following the manufacturer's directions for through-the-liner installation of the skimmer weir door, the water level drained to exactly the bottom of the weir, leading me to conclude that the weir connection was the culprit. <Likely so> I called the supplier from whom I bought the materials, who told me that silicone would not adhere to EPDM <This is correct> (contrary to the manufacturer's instructions) and to use EPDM caulk for the connection. When I called my local roofing supplier, they told me that EPDM caulk is just a temporary material and, instead, to used a particular waterproof EPDM tape. <If the space/gap is very small, this may work...> I have applied this tape - very carefully, after cleaning the EPDM liner with a solvent and rolling the tape with a roller after application - but still notice a slow drop in water level. I have checked the seam where the stream liner meets the pond liner and have re-taped that junction, also. When I turn off the pump (which has a check valve in the line to prevent backflow), the Aquafalls remains full, leading me to believe there is no leak in the bulkhead fittings or the flexible PVC connection to the Aquafalls. <Seems reasonable> The run of flexible 2" PVC connecting the skimmer to the Aquafalls is about 30' long and runs 8-10" below ground level, in newly laid topsoil. I don't see any evidence of wet ground around the path of the PVC tubing. Question (after this very long preamble): Is it possible that the drop in water level could be the result of evaporation? <Mmm, over how much time how many inches of water? And then it virtually stops? It's the skimmer...> Any help you could provide would be most sincerely appreciated. Thank you. Richard Agins <Please send along a link to the actual product if you can... and I will do my best to help you. Bob Fenner>
Re: Pond question, through-put/skimmer leak  - 8/17/07
Here is the link to the skimmer - I have the small (which isn't all that small): http://www.justliners.com/easyproskimmers.htm and here is the link to the extension tube: http://www.justliners.com/easyproextentube.htm <I see... the material the "clamp mechanism's faces" are made of is some sort of plastic... likely PVC sheet...> I didn't mention that I installed the extension tube to the skimmer using a double bead of silicone. <This is what I would have done as well... a few "squigglies"/lines on either side, waiting ten minutes or so...> Both the skimmer and the extension are made of a resin or polymer of some sort, are rigid, and bolted together quite tightly. <No need to be "too" tight> In response to your question, 2-3 inch drop in water level in 2 days with the pump running. I can't imagine that there isn't a reliable way to make the skimmer connection without leaks. This has taken more time than any other aspect of the construction. Thanks again. Richard <And you've tried leaving the system w/o the pump running with the same water loss I take it... 2-3 inches in two days is a bit much... unless there is a good deal of splash, spray involved... and or very dry/high winds... Myself, I would try taking this all apart (yes, once again) and re-Siliconing both faces... and let set up for a day w/ the water low to let set. Bob Fenner>
Re: Pond question - 8/17/07
Thank you. I left the pump off today. I'll review the situation when I get home tonight to see whether there's been a further drop. Your advise is much appreciated. <Real good. BobF>

Question regarding pond liner and UV exposure.  6/9/07 Hi Crew, I tried to find the answers to my queries all over the net and I couldn't find a good answer. <May not be such...> Therefore, I'm writing you to get an expert advice. I just built a 1800 Gal. pond (approximately) with underlayment and liner. <What sort of liner? Material, thickness?> The pond is 28" deep at the maximum and 14' x 7' in length and breadth respectively. I have covered the edge of the pond with stones ,as such , the liners aren't exposed to the sun in any way. I was thinking about covering the bottom of the pond with stones or gravel but according to many experts on-line, this is not a good idea as the debris gets trapped in the gravel or rock and creates an anaerobic condition . <I agree> My question is; would the liner be safe at the bottom of the pond underneath the water? <Safe from?> Some website say that UV rays won't penetrate down beyond 1.5 mm inside the water. When I did the research about UV rays, I found out they can penetrate well up to 15-20 feet deep in water. What do you think i should do to keep the liners safe from UV rays and maintain a healthy pond? <Ultraviolet is not an issue here... but some types of liners (Polyethylene) degrade over time w/o such exposure... and all liners are subject to puncture... with rock, roots, shoes... See WWM re the use of reinforcing mesh, concrete OVER such liners. Bob Fenner>

Re: PVC pipe cement to adhere patching material, not reading...  5/31/07 Wow, thanks for the quick response. I say the liner is PVC, because I described it (black on one side and green on the other side - like flattened out garden hose) to a local landscape/pond company and they thought it was PVC. <...> Does the that description sound to you like PVC. I did try a test, and other than a little shrinkage, it seemed to work OK. I'll check (bench tested) it again at 24hrs post application. What kind of waiting time to refill would you recommend. Thanks again for your timely response. <Please read here: http://www.wetwebmedia.com/PondSubWebIndex/linerpdrepfaqs.htm , and the linked files above where you lead yourself. BobF>

Pond <repair> Question    5/11/07 I have a 7000 +/-gallon pond with a waterfall and coping around the rest of the area. This has been set up for about 5 years and from a biological POV has been very successful. The problem we are having is the coping stones are tipping into the pond. Although they are set in mortar and grouted in between  they are no longer stable. <Mmm, wondering what became of the mortar base> I have spoken to my mason who helped me build the pond and he said we could pin them in but we have a EPDM liner. Do you have any suggestions to lock them into place.    Thank you for any advice you might be able to offer.    Michael Jove <I would lower the water level, remove the present work and lay in a new mortar (actually I'd use concrete and reinforcing mesh... chicken wire or stucco wire... that you can cut with shears... let this set up for a day, and mortar the coping stones with mortar the next day (maybe with a bit of lime or white glue (the mason will know what I'm referring to...) to make all a bit "stickier". Bob Fenner>
Re: Pond Question    5/11/07
Thank you for responding so quickly.< I wish all consult/repair services were so timely>. The mortar base is still there but because it is set on the liner which has give I am sure that shortened its lifespan. Your suggestion of either lath or a rebar equivalent is something we have been mulling over and now will probably use.      Thank you once again. <Welcome... I have done such repairs before... If the present mortar is substantially adhered to the liner, I would just leave it there, remove the coping stones, re-sent in a new foundation built over the present stuck-on mortar bed. Bob Fenner>

Lifting boulders out of pond to patch flexible liner  - 03/24/07 Hi there,   I am hoping you can help me figure out what I need to do to levitate a big boulder so that the flexible pond liner underneath can be repaired.  (The aftermath of a shady contractor.)   I have thought about using an engine hoist, but they are designed to be used on a level surface and would not straddle the distance needed to be on the stable banks about 6-8 feet wide.  I have thought about a installing a boat hoist outside the pond, as well.  I have also thought about (simply) rolling it out of the pond and banishing it to the status of land-based rock feature outside the paradisal pond.   What think ye? Thanks, Jody <Mmm, first and foremost to make cautionary remarks re smashed body parts... Remember thou art mortal! Secondly to state that any movement of this rock, smooth or not, may well tear your liner... So... Do get, place "carpet remnants" or samples about one edge/side... and with lots of coordinated, strong friends... with good backs... lift... with your legs... the rock onto the aforementioned carpet... and scoot more of the same under the edge just lifted... go over to the other side... lift and scoot the carpet pieces further in... Am hopeful this rock is not too large/heavy to allow this prep. work... IF there is sufficient stability, AND room around the edges of this water feature... you may be able to "chain" this rock (securely... with bolts, washers, nuts twixt overlaying links... Tie all this to some sturdy lumber of sufficient length to straddle the pond... re-locate those friends we listed before... and brute-strength, lift this rock out... more carpet pieces laid out in the direction the rock will cover is recommended... DO be careful... and please write back if this rock is too "round", heavy... there are other possibilities. Bob Fenner>
Re: lifting boulders out of pond to patch flexible liner
 - 03/25/07 Hi Kind Crew, Thanks for the prompt reply and the caveat about the squish-crunch factor (ah, the endoskeleton!) <And meso and exo...>   The good news is that there's plenty of room around this flat-ish boulder which is sitting on a @ 10-inch high 'pedestal' of stacked pieces of recycled concrete although it is about 4 inches below the level of the bank.  Would it be feasible to place beefy timbers at sufficient width on both sides of the boulder (with liner gathered up like skirts so timber guides rest on dirt) and slowly, carefully.... many chains, bolts, overlaying links strong backs and many tamales later... <Don't forget promise of cold brewskis later...> have the damn thing out of the pond never to return again? <Yes... Do bear in mind... a useful "rule of thumb" that the rock likely weighs about 200 pounds per cubic foot... and do "loosen" it from its perch... likely with a crow-bar or two... or metal pry bars, digging "sticks"... ahead of attempted lifting>   I could also gather the skirts pad with carpet, pack dirt around the boulder, in effect drawing the shoreline closer, and roll the thing over and over and away. Given the thus exposed loosey goosey liner (all rocks, plants, water removed,) I would plan to install many layers of liner to prevent further episodes. <One good one should do it... Tetra's 32 mil... or a nice, thick EPDM/Butyl...> The contractor used an old rubber-backed rug as cushion on the upper part of the pond, but none beneath this section of the pond which houses the mammoth rock, doh! <Indeed> Nothing like experiential learning, ahem! <Mmm, I'll cut the first-hand experience here m'self>   What are the other options?  This is about a 1-ton rock, <Oh.... really too big... heavy... see below> originally placed with a back hoe... <Can you get one of these back there? W/o too much damage?> The distance from one side of the pond to the other where there is stable ground is about 14 feet, larger than I would've eyeballed it to be.  So 14 feet is the distance any contraption would have to span in order to levitate the rock. <... ohhhh>   So the challenge is to lift it about 6 inches, let's say, and potentially move it about 6 feet to the bank and possibly leave it out permanently. <Mmm, yes> It could look just as pretty at the edge of the pond.   When this rock is no longer there and there is in effect a swimming hole in the pond, do you think that having a layer of rocks, sand and gravel on the bottom would pose a great friction problem should a certain pond-wader find her way into the water when it is 112 thousand degrees outside in summer here in Pasadena, CA? -Jody <I would "cushion" the entire bottom where the liner will rest... Actually, having been involved in a couple hundred such installs... let me "cut to the proverbial chase" here and state that I would definitely NOT make this just a liner pond... but use the liner (as we used to) as the underlayment... Later on this... The rock I would actually "bury"... too big, much trouble to move... not likely easy to break up in place... I would dig a hole near it... and roll it over, in essence, bury the thing under the future pond... And make the pond as detailed here: http://www.wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm The second tray... Concrete and Liner Pond Construction... Read and heed. Bob Fenner>
Re: lifting boulders out of pond to patch flexible liner  03/25/07
Hi Bob, Thanks for the link to the website.  Well, the rock, though 3 feet across, 4 feet wide, and about 18 inches high, must not be a ton b/c it's now sitting pretty on the bank of the pond.  (Two crow bars and three strong backs later.) <Very strong...>   I will purchase the underliner and cushion the liner with a double layer of the underliner fabric.  Is it necessary to have more cushion, such as sand, given that the dirt beneath is FREE of roots, gravel, and other disturbing bits? <Mmm, no... good insurance though... as is staying out of the pond yourself>   And.. I will simply not use the pond to wade in, and that's that. <Heeeee!> Thanks so much for being available and sharing your hard-earned pond wisdom with me! -Jody p.s. I will read again your section on container ponds b/c I have a couple of barrels with black plastic liners (like stock tanks) that I could aqua-fy to good effect. <Ah, good. BobF>

Pond Liner Lifts   2/20/07 Good Day, <And to you> I have searched through your great site and, unfortunately, have been unable to find any information pertaining to our problem.  Our outdoor pond is 8' x 11".  It is 3' deep at one end, 2' at the other.  The pond has a liner.  During our rainy season ground water seeps under the pond and lifts the liner so a lot of pond water drains away. <Yikes... really need to make a drain away from this "underneath" area... to even lower ground... rely on gravity is best... a pump with a float switch if need be> When the ground water dissipates, the liner drops and the pond needs to have water added.  This has been a problem since we purchased our house ten years ago.  The liner now has holes <Yikes...> and we need to install a new liner ASAP as we have loads of fish temporarily housed in an upper pond which is too small for the long-term. We are currently working on replacing the liner but we can't seem to get the area to dry out.  We have the pond drained in the afternoon and then next morning there is a foot or more of water in the deep end. <Yes... same sort of situation, challenge as above... need to either have a purposeful drain, or set up an automated (electrical) pump/switch...> With the water constantly coming in, we are not sure if we can install the new liner and achieve a good close fit. <Not likely, no...>   Do you have any ideas or suggestions how we can properly install a liner and/or resolve our lifting liner problem?  (We live near the ocean and there are numerous underground streams making their way from the mountains to the ocean.) <Ah, yes...> Thank you kindly for you time and any assistance you can offer. Margaret Maringgele <Mmm, if you had a small pump, you might be able to "sink" this into the ground next to the existing hole (digging), place the pump in a plastic bucket... and allow it to pump out the water while installing the new liner... but really the only permanent fix is the drain or automated pump/switch mentioned. Bob Fenner>
Re: Pond Liner Lifts   2/20/07
Bob, <Margaret> Thank you so much for your quick response and possible solutions.  My proposed solution, involving dump trucks and fill, wasn't well received by my husband. <Yikes!> Hopefully he'll like your ideas better and we'll have a liner that stays on the bottom of the pond. <I hope so!> Margaret <BobF>

Sealing EPDM liner to cement... possible, but messy  2/19/07 Hi, Bob <Eric> I am redirecting an existing waterfall through a narrow gap between two very large hard to move boulders into a new creek, so I need to link between two sections of EPDM with concrete between them (concrete to serve as "pond liner" within the narrow 3"-4" gap between boulders and extend several inches out in both directions. I do not want liner to be visible in gap between boulders. Can I bond the liner to the smooth cement with asphalt emulsion UNDER the water level? <Mmm... possibly... a real mess though... wear your absolutely worst clothes... very long, up to the elbow and beyond... "ladies" dishwashing gloves or similar for chemical handling...> If  not, what's the best adhesive? <This really is (amongst what is widely available) the best material... there are a few formulations... You want the very "viscous" material... likely labeled for roof patching...> Or alternatively, if I were able to dress the EPDM thru the crack between the boulders, how can I seal it to the rock BELOW the water line? <A VERY good idea to do this at the "low water level" time of the year... BEST by far to divert or dam the water for a day...> Asphalt emulsion , construction adhesive calk, RTV calk, polyester resin??? <Only the first will work IMO> If I go the cement route, is there risk the bond between cement liner and the boulders will crack from settling or whatever creating a leak? <Always, yes... best to fit this with large, well-shaped rock... and fill the gap (best to actually make a "form" first, and build to fit closely OUTSIDE the system), with a very fast settling cementaceous product like Thoro's "Water Plug"...> Perhaps I should cast in a 1/2" gap between the concrete and boulders on each side and calk it with flexible sealant like that used on swimming pool decks? <Bingo! A wise choice> Thanks, Eric <Welcome, Bob Fenner>
Re: sealing EPDM liner to cement
  2/20/07 Bob, thank you very much for the invaluable advice. Amateur on this end. Regards, Eric <We are all amateurs at all things at one time... Welcome! BobF>

Pond Liner I'm just starting my outdoor pond.  The pond is built on cement floor and surrounded by cinder block wall as an extension of my planters.  What adhesive can I use to adhere the liner to the cinder block walls? <Mmm... would be best to "capture" the loose edge under a cap if still possible... mortared over the edge with plastic cement, thin-set and Acrylmix... If you can't do this, please write back and we'll talk. BobF, leaving Houston>

What type of liner to use   7/24/06 Hi Bob, <Craig> I'm getting ready to dig a hole and I am a little confused with the different synthetics that go into the liners. Some background.  My 4000 gallon pond needs a liner.  Which of the liner material would you recommend - EPDM, PVC and HPDE/LPDE? Thank you, Craig <Mmm, here: http://wetwebmedia.com/PondSubWebIndex/linerspdconst.htm and the linked files at top. My preference (by L'Oreal?) is in the order you present these. Bob Fenner>

Will blocks cut the pond liner  5/29/06 Bob, We are building a pond using blocks.  The pond is 15 x 25.  Will the top of the blocks cut the liner over time? We will be using 42 mil liner then "topping" it with flag stone.  Thanks. <You should be fine here... this sort and thickness of liner is VERY tough... I would first lay-in the liner (w/o mortar), fill the pond, place the flagstone... allow all to sit for a few days... see if this is about what you're looking for... remove the flagstone, trim the liner where it is overlapping over the outside of the flagstone... and re-place, mortar it in place... with or without reinforcing mesh (Leaving the cap non-mortared is too likely to lead to pieces falling in, this potentially puncturing the liner. Bob Fenner>

Sealing edges of rubber liner fix  12/21/05 Hi,   I live in NC and purchased 10 beautiful acres with a 50 year old, 1 acre pond on it. It is filled with runoff water. When It rains it fills up nicely , then after a few days the water level drops about 2-3 feet. I see where the water drains out on the backside of the 20 ft. wide dam. Large trees sat on top of the dam and spillway which I recently cut down. I do know the reason for the leaking is the large caverns these roots have caused. I can't afford to redo the whole pond and a farmer suggested laying a piece of 10' X 100' rubber liner across the dam area and down below the surface a few feet to stop leakage or cover holes. My question is, once I put this down and secure it with rocks here and there, won't water just seep under it around the edges and the leaking will continue just as bad as before? <Likely so, yes> Do you think this might slow it down to a natural leakage pace? <Doubtful...> By the way I do know cutting down the large trees will cause the roots to die and make more ways for water to escape, but the amount of leaves falling into the pond each year is tremendous and trees and root systems were hanging out over pond ready to one day fall in. I'm sure the leakage and/or holes is below the root balls sticking out. Please help, the few fish remaining need some deeper water to survive. Becky <Mmm, I suggest you "let your fingers do the walking"... have some local contractors (likely to be found under "landscaping" in the Yellow Page Directory)... and have them tell you your options. Maybe a clay-based material can be dished into your "over-burden" (the unconsolidated material on the pond bottom), or this overlain over the base of the liner on the dam... Bob Fenner> sp;

Pond Liner attaching to existing concrete block wall   11/12/2005 Bob, First, I'm a big fan of your books. Even though I've never meet you I've heard a lot about you when I used to work at Octopus's Garden. <Ahh, and Ron now has a much larger, very nice outlet... on Convoy> I have been in the Reef Tank Hobby for 4 years now and have a nice setup that is thriving because I followed your advice found in your books.  I am now putting in a 3000 gallon pond in my backyard. The hole is dug <The hardest part...> and the liner has been shipped. The problem I have is that the liner has to attach to a the cement block wall of my garage. What method would you suggest I attach it to the wall with. I plan on attaching that side first and leaving the rest able to adjust and settle when I start to fill the pond. Thanks, Dave MacLeod <A bit messy, but the simplest means here is to "glue" the liner to the block wall face (well above the water line) with asphalt emulsion... don't wear your good clothes... do wear gloves and have rags, gasoline to clean up handy... Alternatively, much more liner can be sacrificed by having this go up above the block wall and a cap placed over it, on top... and the facing of the wall, liner, concealed in some way. Cheers, Bob Fenner>   

Tom's new pond, WWM Thanks  8/31/05 Bob, just wanted to take a minute to express my appreciation for all your time and patience with me over the past few months concerning my new Koi Pond. <Welcome> I realize you go through hundreds of emails a week and may not remember the exact "conversations" we've had.  But suffice it to say that I appreciate all that you and your crew do! <A pleasure, duty and what we like to do> Thanks to your advice and all the articles and FAQ's here, the pond has become a reality.  I still need to back-fill the ditches for the plumbing, install the "siding" around the outside, and get the gravel in the filtration compartment, but just wanted to send along a couple of pictures and my heartfelt thanks. Here are a couple of links to the pond if you're so inclined: http://i5.photobucket.com/albums/y195/navajo001/pond101.jpg http://i5.photobucket.com/albums/y195/navajo001/pond102.jpg <Good liner wrap and wood construction job!> http://i5.photobucket.com/albums/y195/navajo001/IMGA0078.jpg <Some very nice quality koi... do keep your water level down a bit to discount their jumping out> There IS one last question I couldn't find the answer to anywhere.  The pond is approximately 1500 GAL plus whatever is in the filtration compartment.  Will I experience much of a cycle in there with only 4 small fish? <Not much, perhaps not noticeable> Or will the water volume be enough to "handle" the nitrogen cycle with little impact? <Should be fine. Can monitor if you'd like> I did go ahead and place a filter sock with media from their canister filter in the waterfall just in case, but not sure if that was needed. <A good idea> As always, Thank You for your time and dedication. Tom (The Tool Man) <Congratulations on a job well done Tom. BobF>
Tom's new pond  8/31/05 Thanks, so much, for the "atta boy"!  HA! I have actually lowered the water level since the pictures were taken, but I still don't think it is enough.  When the fish swim up close to the edge, I still get butterflies thinking how easy it would be for them to jump out. <Koi can shoot out like veritable Polaris missiles when rambunctious> How far down from the top would you suggest?  Would 6" or so be enough?   <At a minimum... am given to understand you intend to "build up the berm" with some sort of landscape/surround...> I know that if they are determined to jump or get spooked, all bets are off.  Just trying to find a happy medium (as with most everything in this hobby!) Once again, thank you for your patience and dedication. Tom (The Tool Man) <Welcome... in time the fish will generally "learn not to jump", but in new systems, with shallow sloped edges (not like yours), sharp corners (like yours), they can/do easily jump out if spooked, excited. Bob Fenner>

Have you heard of a powdered pond liner 8/17/05 I would like to know what this product is and how to use it. If you have any information on it. I would appreciate it. Thanks, Sylvia <Mmm, there are materials like powdered lime, clays that are sometimes (though less frequently as time goes by) turned into existing soil to make a water-proof or more water-proof barrier... What is the application here? Something very large? Bob Fenner>
Re: Have you heard of a powdered pond liner 8/20/05
This stuff looks like sugar granules. You just put it in the pond and circulate the water. And it stops the leaks. I put it in the pond today and the water looks like syrup. I sure hope it settles. Sylvia <Yikes, I sure hope you read the instructions, precautions. Bob Fenner>

Leaking 25ml polyethylene liner 8/17/05 Hi crew, I've had a leaking pond for 7 years. It is made of 25 ml polyethylene and I know where the leak is at. I have tried to clean it very carefully and re-tape it with 6" tape from the company I bought the liner from several times. The tape has worked great except for one place. It is on the north side of the pond and it almost never dries out. What type of solvent is best for cleaning the liner to prepare it for tape? <... alcohols are about the safest, most thorough...> I have been using rubbing  alcohol, since it dries so fast, but I'm thinking there must be some type of solvent that is specifically suited for polyethylene. Also since the area that has to be re-taped has many curves and 25 ml  polyethylene is so rigid is there a better material that can be used to go over the polyethylene, but will stick to it. <Not as far as I'm aware> My pond is approximately 120'x30'x9'deep. Replacing the entire liner is out of the question, it has a  shelf all the way around it with rock placed in the shelf and a rock walkway all around the top of the pond. I have spent literally hundreds of hours of my time getting it to this point.  The repair has to be made in place. If you can give me some suggestions I would greatly appreciate it. Dynamite is my next option. HELP Thanks in advance Tim <I wish I had better news for you, but there is nothing that I'm aware of that will help, or repair a polyethylene liner... One of the reasons I am so opposed to their use in biological ponds, basins. Please read here: http://www.wetwebmedia.com/PondSubWebIndex/linerspdconst.htm Bob Fenner>
Re: leaking 25ml polyethylene liner 8/17/05
That sure made my day, your site is a great source of info. thanks <Am very sorry for your troubles... we replaced many "poly" liners over the years... no fun, to put it mildly. Cheers, Bob Fenner>

Lessons in liner differences... some are toxic to pond life 8/5/05 We are new to the Koi Hobby, and just built our 1st pond in May,  we have had 7 fish since July, but developed a slice our current liner, so we had men come out and put in a new PVC Blue liner, <Is this a swimming pool product? Some are treated with chemicals that are undesirable for biological systems> We moved the fish to a large horse tank  for 3 weeks, while we went bigger and deeper with the pond. we went to our first Koi Pond tour, and got new info and designs. <Ahh! An "eye-opener"... which invariably folks wish they'd done before setting up...> Needless to say, they finished installing the new liner on Sat, July 30, and we got the filters going,  the water was clear on Tuesday night, and water test are good, so the fish were transferred back to the pond. We came out on Wed night and the small fish were dead,  The large one was still doing ok, swimming around. We took the water in for testing on Wed night, and all the water tests are normal.  I questioned the oxygen,  it is a 1800 gal pond. But that came within limit, he indicated that bigger fish would have died first if not enough oxygen. <This is so> The water filters completely 2 times a hour with the pumps/filters.  Today the large Koi is dead.  The pond people said that maybe the liner is toxic, <Yes> How can we Tell,    the liner people said it is non toxic.   <Non toxic to what? Swimming humans... you can "do a bioassay" with water taken from the exposed liner, or soak a piece of the liner in water that you know otherwise to be okay... or ask to see the manufacturer's information re this liner... or take the liner to a QA lab...> We have well water,  have added  nothing except Koi Clay.  He gave us black crystals to put in a hose and put in the outlet water, to capture any toxins. <...?> Help!!   My husband is terribly upset as are the children.  If it is the liner, how can we fix it?? <Can either wait, see if time going by, perhaps chemical filtration will remove... plasticizers, anti-mildew/algal material... or remove, or place a non-toxic liner over this in turn...>    If it is the liner, can it be treated, so we do not have to tear it out,  does it wear off? <Likely the latter does occur... but how long...? Bob Fenner> Carolyn

Lake liner 7/9/05 Hi- <Hello there> I stumbled upon your great site and Im hoping you can help me out.  My boss is planning to build a rather large lake on his mountain side property here in Ojai.  The lake dimensions are 200x100x150 and were trying to determine the best type of liner to use.  The soil in the mountainside is rather impermeableweve had difficulty passing perc tests because the ground is so hard.  Our contractor and ranch foreman recommend using a 30 mil PVC liner, but my boss is hell-bent on using a clay liner. <Mmm, I'm much more inclined to go with the PVC>   How much would a clay liner run on a lake this size? <... depends on the make-up of the current basin bottom... a mix of material has to be dished in... Likely cheaper by far than the PVC> Is it even worth using? <Yes...>   Hes talked about bentonite and gunite.  Thanks for your input! <Not the latter... very expensive. I would have a few of the "lake consulting" and construction firms come out, bid this job. Bob Fenner> Emily Warmann

Repairing a pond liner, literacy HI,    We have a pond in our back yard that has a rubber like stiff liner. And it has a leak. Is there anything I can use to repair it.     thank you  Marty Soloman <Please see WWM re... the Pond Subweb... Liners... Depends on the make-up of the material, the nature of the tear... Bob Fenner>

Concrete block pond construction I have read with great interest (and thanks) your section on building a pond with concrete block. The walls will be concrete block and I am going to use an EPDM liner. How does one attach the liner to the block under the coping? <Basically, liner is underlain twixt the topmost course of block and whatever you're using as a cap (likely more cementatious material or rock, mortared in place. A good technique is to slowly fill the pond without this cap, pulling the liner in place to flatten out, leaving it almost all the way filled to assure a good fit while applying the cap. Bob Fenner>

Custom-shaped pond liner Do you know of any companies that make custom shaped pond liners? <Yes> I am building a 600g indoor water feature (for Koi) in my new office.  It is oddly shaped and five-sided, about 3 ft deep, and I was wondering if I could get a 3 dimensional pond liner custom made to fit it rather than face the creases caused excess liner? Thanks very much... Jeff <Umm, the companies that fabricate liners consider this size piece a scrap... You are best off buying a small liner (I really like the Tetra product for consumers making liner-only systems), and folding, cutting it to fit... these do come in a few sizes. Maybe see Tetra's site re. Bob Fenner>

Pond liner in tank Situation: Excellent site with good faq's but mine is a bit specific... Built a plywood tank and used pond liner (instead of epoxy), and sealed it up with GE 1200 Silicone.  (I got it from a tank builder so I assume its aquaria safe).   <Is, but doesn't adhere well to liners> I just poured RO water and after 2 days the water started clouding a bit.  Is this a result of the silicone? <Nope> Is this normal and will running the water through carbon clear it up? <Is normal, carbon will help... but really the "system" needs to cycle... this takes a few weeks... can be sped up... a "break-in" biological period.> Right now the water is just standing with no movement. <Better to recirculate it> Or, is the EPDM pond liner giving something off.... I assume the liner is safe to use for fish seeing as they use it for ponds....  Do I need to prepare it before use? Please help! Thanks Lee <EPDM is very safe... Please read on WetWebMedia.com re cycling of aquariums... the same series of events occur in all aquatic environments. Bob Fenner>

Seaweed ponds Hi. <Hello there> We have built 2 (50 x 20 metre) ponds for a trial in seaweed production, using saline groundwater.  At present the ponds are not lined, but I feel that they are leaking and could cause environmental problems.  As our local black plastic (polythene) comes in 50 x 4 metre rolls we will have to join 5 large sheets together.  How would you suggest this could be done?  Maybe they could be heated together!! <No my friend. Our companies (among other ornamental aquatics work) designed, installed and maintained large water features, including seaming nominal 20 mil PVC... we also bought and installed Butyl Rubber, EPDM and other liner materials as underlayments... but never Polyethylene... even the types that are treated to resist "aging" and sun are disappointing... too short effective time spans, too easily punctured... and NO (unless technology has changed...) means of welding (sonic, solvents, heat...) sheets together. The only good things about Polyethylene is that it's cheap and readily available. I encourage you to look into other liner materials. Bob Fenner> Thanks Charlie Gillingham Lake Charm Victoria Australia

Question on toxicity of pond liner repair I have a question. I have a 100 gallon pond set up in my remodeled  attic with some of the smaller fish I bring in for the winter from my  outdoor pond. I had to fix a minor hole near the top of the plastic liner.  I was wondering if the epoxy glue that I used can affect my fish in any  way. Thank you for your time.   Len <Should be fine, non-toxic once the epoxy is set-up/cured. Bob Fenner>

Pond Liner Mr. Fenner, <John> How about 36 mil polypropylene for a pond liner? This product is manufactured by Bend Tarp and Liner, Inc. as a liner for holding ponds, etc. They will cut custom dimensions will should be a plus because of the layout my pond will have. I won't have to make any seams. It's also cheaper than many products I've found. Thanks, John Jordan <I like PVC, EPDM, Butyl Rubber... more for their stretchability and resistance to puncture myself. Most any waterproof material will do however, if used under a shell of wire-reinforced concrete... the best available, most-appropriate technology in most applications. Bob Fenner>

Swimming pond 7/28/04 I have a large area where I would like to put a pond.  It has a natural spring that will feed into it via a stream I built with 20 mil liner.  I would like to swim in it.  What liner options would work?  Would I need more sand?  The size of it would be about15ftx20ft. Thank you for your help. Alysia, Asp  <The same (likely polyvinyl) 20 mil liner would likely work. Other choices available include Butyl Rubber and EPDM (these are generally more expensive though)... A few concerns to voice: Depending on what the ground is like (sharp rocks, roots, invasive plants about...) you might want to "jump ahead" and plan on either shotcreting (over wire) the basin or at least the "bench" (edge)... if not going the gunite route. Do have your water checked (unfortunately) for possible human disease issues due to the source... and lastly, do make provision to prevent vector problems (stock with mosquito fish...). Bob Fenner>

Pond with a view Hello there, you have been so helpful with my marine problems; I can't help share my pond concerns and thank you in advance for your wisdom. I'm in the design phase of a pond approximately 5000 gallons that will have a viewing panel in the adjacent attached sunk in patio. My question is - how the heck to you get a good seal on an acrylic view port that will be about 2' high and 3' wide? Is Acrylic even the best material for outdoors without direct sunlight? We are in Tucson and are hoping to go with a cichlid pond as opposed to the Koi pond which is why we so desire a side view into the pond. Thank you for your time. Bill Roh <I've done this a few times years past. Best to have a "race" frame built, pinch/fit your liner into this and nestle the viewing panel into the frame with silicone. Bob Fenner>

Re: Question regarding pond liners Thank you for your recommendations, I'll look at the postings for shotcrete. Since I've written to you, we've interviewed a contractor who suggested troweling a concrete underlayment under the rubber liner to deter gophers. She is having to replace her mother's pond for that very reason (gophers). <Not under, but over... please read through the WetWebMedia.com site re pond construction en toto, particularly with liners> The screen-wire mesh underneath the liner was to deter gophers from chewing from below, but I don't think it would last long before deterioration. Thanks, Linda <Bob Fenner> >Question regarding pond liners >Dear Sir: >I found your address on the WWM site, I hope you're the right person to ask the question. >We live in SE Arizona, and want to build a pond with waterfall feature for birds, and also encourage dragonfly and damselfly larvae. We do not plan on fish other than maybe a few Mosquitofish or similar. The size is about 20x10'. The local pond builders recommend the EPDM rubber liners. We have deer and also gophers. How do the liners stand up to these two mammals? We could possibly have javalinas, although they haven't' been in our yard in a year, they do live in the Huachucas. ><All these mammals can easily puncture a liner of any material with their claws, hooves> >If a screen-wire mesh is put below the liner, it seems like it would rust out quickly. ><Don't understand what the rationale for this screen is... we built many such ponds using liners (generally 20 mil nominal PVC...) not often but sometimes using an underlayment of carpet... to prevent outright puncturing of the liner during construction, rock placement. Almost invariably we shotcreted over and into a wire mesh >over the liner... I suggest you look into this technology (posted on WetWebMedia.com) and do likewise. Bob Fenner> >I appreciate your advice. >Linda Feltner

Vinyl Liner Ponds I got your email address from the website, WetWebMedia.com. I was hoping you could point me in the right direction for an article I'm working on for Pool & Spa News on How to Install a Vinyl Liner Pond. I am looking for builders to interview who can provide a step-by-step instruction on the construction on a vinyl or rubber liner pond. I have a couple of builders I have spoken to already, but need a few more to round out the story. <What I know, have written is placed/archived on WetWebMedia.com> My deadline is quite soon--Tuesday, January 27 at noon--so any assistance you can provide will be helpful. Thanks very much. Janice Rhoshalle Littlejohn <If you have specific questions, send them on to crew@WetWebMedia.com Bob Fenner> Janice Littlejohn Pool & Spa News www.poolspanews.com

Low cost operating pond pump 750 gal. Hi! I'm new in ponds matters, and I'm building a pond of approx. 750 gallons. I need your help. I need the best cost efficient pump for this size pond and the best liner EPDM or the Tetra Pond Xavan liner? Thank you for your help.   <I'd look to the fractional horsepower units offered as "Sequence Pumps" here if you can use their smaller size/s... And the Tetra product is not inexpensive, but is an excellent choice. Bob Fenner>

KOI Pond Construction Bob, This is Keith Slinkard , Eric's Father-in-law . <Hello Keith!> I have some question about the mods that I am going to make to the design and enlarging my fishes habitat. 1. I purchased Firestone EPDM liner and I am concerned about the wrinkles that I think I will have . I think that I want to shot crete over the EPDM ,but can not find directions as to what to do with the wrinkles prior to applying the crete . <No worries... on a nice warm day (careful not to lay the liner on your grass!) the material becomes much easier to make folds in then> 2. The size is as follows , 18' long X 8' wide X 2' deep with a 1' X 1' plant ledge around the perimeter. All walls are completely vertical . I think this will add to the wrinkles and make the shot crete application difficult. Should I angle them somewhat ? <No. Best to try and make as vertical as possible... the wire and shotcrete will conspire to make the walls and corners more sloped... In fact, a good idea to use a lower slump concrete/shotcrete mix... and "lay a bead" on the bottom corner seams in an attempt to "build up" the mass of material... much easier than "pushing up" the material after the concrete truck, applicator is gone> 3. I am going to change to a pond filter to like the one you exhibit in fig.10 of your Aquatic Gardens book on page 10 . With the volume of water that I need to move , do you suggest a dry pump, and if so what size ?   <Yes, not a submersible, and one with as small an electrical current as you can get by on for the volume (at the head) you're shooting for. Please ask Eric to show you the "Sequence" series pumps... if memory serves they have a nominal 1/5 HP unit that should work nicely on your application> 4. Where do I place the supply line to the filter and how do I install it through the liner material to insure a water tight fitting . <Mmm, best to run the plumbing "inside" the liner, and up and over the side of the system (a bit tricky to prime the first time but worth it). Water for the intake should come from as far away from the return as practical... and from the bottom as well as a side intake (a foot or so down in the water), these with a valving manifold to isolate one or the other (to vent water occasionally)> Thank you in advance for your expertise and direction . Keith Slinkard    <Glad to help. Bob Fenner>

PVC liners hi--we're not creating a pond (have 2 clay ponds already) but need to use pvc of 20 mm thickness to surround our old house to prevent our major basement leaks.  plan to bury it to a depth of 12" then cover with gravel.  I need a piece(s) 6' x 40' -- where can I find such a creature?  thanks for your help--Lucinda <Can be done (one of our old business (non-extant) used to fabricate such thickness PVC liners for all sorts of purposes (even roof waterproofing on buildings). I would contact the companies listed on our pond links: http://www.wetwebmedia.com/PondSubWebIndex/pondlinks.htm (Under manufacturers, etailers... and the clubs if any, in your area that have members that may have bought such size shaped liners). There are "scraps" of about the size you list that can be had, or welded together... so keep checking till you find someone who is really "in the business" or actually does fabrication. Bob Fenner>

Rock-looking pond liner - anyone? I am looking for a pond liner that looks like rock, not the normal black color.  I saw company was selling them, but I can not re-find its web site.  Do you have any info on such an item? <My apologies (in lateness as well as failure) - I've searched and searched, and simply cannot find what you're looking for.  Hopefully someone who does will see this and let us know, so we can pass it along to you.  -Sabrina> Thanks, Dave

Concrete gold fish pond I have asked this question to everyone I can find that knows any thing about concrete or ponds. Now I found this site so I will try you guys. Here goes : This summer I uncovered an old kidney shaped pond in my yard. It is aprox. 4' wide & 9' long. It now is about 30" deep , but appears it should be 6" to 8" deeper to be above grade. Before it was covered up who knows how many years ago, the top edge was broken off so it could be covered with dirt. The walls are made of a concrete & something mixture with 3" field stone mixed in for filler. The inside walls are nice & smooth, coated with a light gray mortar type material. My question is what is this concrete mixture? It seems years ago I heard that concrete & vermiculite where mixed sometimes to make a lighter & more workable mix. If that's true how do you go about something like this ? Any other advice on a pond of this material would be helpful! Thanks in advance .Steve from Ohio   <There are a few possibilities as to the mortar mix that you describe, however only one tried and true "re-make" possibility to ensure the watertightness of your refurbished pond. It's detailed here: http://www.wetwebmedia.com/PondSubWebIndex/concrepart.htm Skip ahead and around to the pieces on liner use/construction. Bob Fenner>

EPDM pond liner return channel... Good Afternoon, i would like to install a pond utilizing an EPDM pond liner but have limited room to provide a typical return for the end of the liner.  Does some sort of prefab, return channel system exist or has anyone made one that works well?  If so, what materials did you use, etc. etc.?  Thank you and i look forward to your response. Regards, Carol <... A "return channel" as in a way to run plumbing back sight unseen? You can install a through hull fitting/drain through the liner and attach plumbing to this and remote it where you want. Or do you want to affix a channel as in a stream to your existing basin? This can be accomplished by overlapping a section of liner over the side of the existing basin... or there are other, mainly fiberglass streams, filter boxes that can positioned adjacent to your pond. Some of these are more fully discussed, illustrated on our pond subweb. The index to this is here: http://www.wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm Bob Fenner>
Re: EPDM pond liner return channel...
Hello Bob, Thanks for the speedy reply!  It's obvious I'm using the wrong terminology...i need some way to secure the liner without draping and securing the liner over the pool edge.  The pool is rectilinear in shape with vertical concrete pool walls.  i thought there may be some way to fasten an aluminum, u-shaped (?) channel, or some other apparatus, that will hold the pool liner in place above the water level.  The corners are also going to be a nightmare to be sure.  Any suggestions???  Thanks again Bob! Regards, Carol <Oh, I see. Yes, there are ready-made tools and materials for what you want to do. Use your phone directory... and if there is one in your area, under "Swimming Pools" you will hopefully find a company that installs and/or repairs vinyl swimming pool liners. They can show you the "tricks of the trade" here. Bob Fenner>
Re: EPDM pond liner return channel...
Good Morning Bob, You are a life-saver!  Thanks for the info and support.  I'm sure we'll find a solution now. <Glad to be of assistance. Excelsior! Bob Fenner> Regards, Carol

Pond fish dear crew,     A fantail and a comet goldfish in my pond seem to have white pimple like spots on their gills.  I am unsure at what this is, but i have heard this could be related to spawning. Any ideas? <This time of the year (Spring, warming) this is very likely the case. There are some pondfish ailments (e.g. fish pox) that can look similar, but highly unlikely here> When i was visiting Canada recently i saw a huge goldfish that must have been released there.  We almost caught it with our net. I would have loved that fish for my pond.  Also, next year we are upgrading our pond to about 3000 gallons. What type of liner would you recommend? <The thicker... at least 20 mil, the better... butyl rubber or EPDM, but vinyl will do...> I am currently using EPDM rubber, but if there is a better type i would like to know about it. <Oh! This is fine. Bob Fenner>                                                             thanks                                                                     Holden

Re: LINERS TO GRANITE??? First off, THANK YOU!    I love your website! I came across your Pond Articles & FAQ's page and havent stopped reading yet! Im landscaping a development on a small island off the east coast of Thailand and it seems every homeowner wants 2-3 water features on their property! <Very nice> I have a lot of huge (and I DO mean a LOT and HUGE!) granite boulders throughout the site and most of the features will utilize these. <Have been to parts of Thailand, the Similans... not yet to Koh Samui... but have seen what you're referring to... BIG> I plan to use cement ponds and streambeds with liners, but I want many of the boulders to be exposed from the waterline on up so as to avoid unsightly cement seams. My inquiry regards methods of sealing the liner to the granite faces of these boulders. Have you come up with any system/materials that would apply? I have been reading everything I can from your site, but may have missed mention of such a problem...please excuse me if you already answered this somewhere else on the site! <No worries. We had some success with either joining the liners to such rockwork on either their "front" sides or if you can safely lift the rock, place on the liner (with some cushioning below, like old carpet) "behind" the rock, with the technique described on the WWM site of attaching the liner to steel rod, coating with masonry/concrete, or simply backfilling with soil.> Ill include a few photos that show the boulders so you can get an idea of what I mean. <Ah, yes> Thanks again! Shawn Mayes Nagalaya Co. Ltd. Koh Samui, Thailand <Please make it known if this is unclear, incomplete. Bob Fenner>

LINERS TO GRANITE??? Apparently, you had some problems with my reply in all caps, sorry about that... I'll try again... I'd like some further elaboration on the first technique you mentioned, (I.E. "We had some success with either joining the liners to such rockwork on their "front" sides "), as these boulders a far to large to lift. I'd be most interested in materials and techniques/processes (i.e., do you have to grind the granite down to a semi-smooth surface to get a good attachment or have you used some form of thick liquid glue material? <Good idea to "acid/bleach wash" (notes on WWM re) the rock that is being attached to, and use asphaltous based material (like roofing "lap" cement) to stick the liner to the rock (be careful applying, this stuff is messy). For small jobs, using a chalk line and water level to find, measure the upper reach of the liner, making a mark a few inches/centimeters above this to give you an indication of where the liner is, perhaps using caulking gun sizes of the lap cement to apply a bead of sealant (rather than a open bucket and trowel for larger jobs) right below the lower of the marks.... let the lap cement set-up for a day, trim the excess liner... Bob Fenner> Thanks, Shawn

Pond Liner Leak Hey Crew, <Howdy> I have a slow leak (About 100 to 150 gal. a day) in my reinforced woven 40 mil. plastic pond liner. The pond is approximately 4,000 gal. I noticed this problem after we had several days of cold weather in the lower 20 degrees. I am in S. GA. I drained the pond and repaired all the small holes, etc., I could see. I checked the seams from end to end. There are no leaks in the plumbing, UV, bio filter, etc. I still have the problem. Do you have any suggestions?? Is there a sealant I can use? Thanks, Charles <Unfortunately, theres no actual sealant that I know of but do check out http://www.wetwebmedia.com/PondSubWebIndex/concrepfaqs.htm as theres a lot of info on repairing leaky ponds there. Also do a search at www.wetwebmedia.com for pond liner leak or pond liner repair. Ronni>

Pond Liner Bubble We have a 1 acre pond which was lined with a nice thick liner a while back. <Nice> In the past few days however it has developed a 25' diameter bubble in the middle (see attached picture). Any ideas on how to fix the immediate problem and prevent a future recurrence? <Yikes... I wonder as to the cause... the make-up of the gas itself... Some way needs to be devised to install a vent...like a "sideways drilling" operation... a pipe to the area directly underneath this bubble, water, liner... to allow the gas to escape... Perhaps a well-drilling co. in your area can help... If you had known of the gas problem, perhaps shaping the basin to be more conical would have prevented this condition. Good luck, and do have the gas checked... it could be something flammable. Bob Fenner> Thanks, Glenn A. Hartzog

Pond shoreline design problem Hello folks <Cheers, my friend> I have been referred to your site by someone who answered one of the posts I have placed on several boards regarding this problem. <welcome my friend. Do be sure to visit the home page at www.wetwebmedia.com and navigate the links to our many articles and FAQs. This is one of the biggest websites that you will ever see... over 300 megs!> Before I ask my question I noticed someone with a home made food question, could I refer you to http://www.easyfishkeeping.com/fishyforum/forums/message.asp?r=forums&t=General&I=1040 I now know about WNV but my fry have more than doubled in size on this diet in the past week. WNV is not a problem in the UK that I know of. <outstanding... thanks kindly> Anyway to get to my question or problem. Back ground first I have built( finished building last night, just touch ups and this shoreline left) a concrete pond of aprox 2200 UK gal 2600 US gal. It has three depths, 4', 2', 1' and vertical walls. I will be using a plastic liner, pvc or Dupont Xavan, I can afford butyl. The pond is above existing ground level by 1' and will have a visible wall on 2 sides, a hedge on the 3rd and a rockery with waterfall on the 4th. I will 'line ' the concrete with expanded polystyrene sheeting ( Styrofoam, I think ) to protect the liner rather than use underlay. <indeed, many materials used here... old carpeting, parched clay, rendered sand, layers of newspaper, etc> BUT Basic outline of my problem. I want to cast, in cement or concrete, a ramp on top of the upper coarse of block work to create a semi submerged shoaling shoreline. I intend the ramp to start 2.5" below the water surface and for it to rise to 0.5" above the water surface, gradient 1 in 3. It is to allow animal access/escape to/from the pond. <very nice> For the purposes of this post I am concerned only with the construction problems, I have taken into consideration my possible UNWELCOME visitors and here in the UK we don't have the diversity of predators that exist in N. America, I hope the rest of the pond design will keep my fish safe. <very well> I see 2 ways of completing my shoreline 1) bring the liner up over the ramp, or 2) bring the liner over the top of the inner leaf of block work and drop it into the air space, then cast the ramp on top of the liner and outer leaf . I favour the second method, it will be neater and provide a better surface finish. Obviously I will seal the ramp with some thing like G4 or P1 ( common UK sealants ) but I am troubled by the "triple point" where water, liner and ramp meet. <agreed as I am concerned too. There is also the concern of longevity and repairs/replacement of the liner. The plastic and PVC liners in particular have had issues with longevity and UV stability. The latter method would not be at all forgiving if repair or replacement needs addressed> How do I seal this properly? I had thought of 'painting' the sealant across the junction and onto the liner but I have been told that solvents in some solvent based sealants may damage the liner, i.e. G4.  <agreed> I can get water based sealant which should be ok, P1. <yes... but I am still not sold on the practicality of the design inherently> Other solutions based on idea 2 are 1) In addition to the above run a bead of silicone aquarium sealer around the "triple point" , possibly in a rebate cast into the cement and cut out of the polystyrene <poor adhesion to plastics particularly in temperate zones> 2) Bring the liner up 'behind ' the back of the ramp so that the liner finishes above water level, but this may create neatness issues also it doesn't provide a secure foundation for the shoreline. <actually I like this solution best thus far> 3) Cast the shore line in sections, seal all of each section and then 'glue' it down onto the liner with silicone aquarium sealer. <likely very temporary (3-5 years before failure IMO)> One area I will have to silicon goo is the folds in the liner where they pass over the block work. Additions resulting from replies to my posts are 1) cast the ramp in waterproof concrete, a simple idea that will help greatly, why didn't I think of it and does away with "3)" above <agree... hydraulic cement was the first thing that crossed my mind above when I read "ramp in water". Quite durable in water> 2) cover the triple point with liner seaming tape. <also a temporary solution in my opinion and unlikely to even see 5 years of service> I would be very grateful for your thoughts on my problem and solutions and for any ideas that you have. Thank you Sean McKinney <I don't know if I've been much help, but I sure have enjoyed hearing about your fascinating pond. With kind regards, Anthony>
Re: pond shoreline design problem
Thanks for your reply to my last email, <our pleasure> your point about liner longevity is well noted, the adhesion of silicon goo to plastic hadn't occurred to me, thanks for that, I have just had a trial run at liner installation using 2 sheets of 6m x 4m polythene joined with brown parcel tape to make a single sheet 6m x 8m. Judging by the folds I have had to included I may well have to bring my liner " up behind the back of the ramp " . Your favored solution. I very much doubt that I could seal all the folds with the silicon goo. <agreed, my friend... none else seem to be a good 5+ year solution for a liner that is otherwise good for so much longer> Thanks for your input. <with kind regards, Anthony Calfo, Wet Web Media>

Leaking Pond Liner Do you know of any product that can be sprayed or painted onto an existing pvc liner to make it water tight? The liner is only a few years old but it no longer holds water. <There are no such "miracle cures" as far as I'm aware... but most liners can be repaired pretty easily by solventing (aka "welding") a new piece/sheet of material over the cuts. Please read here: http://www.wetwebmedia.com/PondSubWebIndex/linerspdconst.htm re pond/liner construction... and the links, other files beyond. Is yours a Butyl, PVC, EPDM liner? You will need to know this, and find a compatible/matching material to anneal to it, and solvent to do so. Bob Fenner> Thanks, Fiona Casarini

Pond Liner for Salt tank set up? Bob, First off LOVE THE site!! Just found it and it's a wealth of info. I have a quick question 4 yaw. I'm considering making a large salt tank and was wondering if the normal pond liners would be ok for constructing a salt tank used for sharks and rays etc..... If pond liner won't work is there any other material other than the Rubbermaid tanks etc...... I want an indoor pond but with sharks I figured the cheapest way to get a 6x12 tank would be to go pond liner.. Thanks and keep up the good work. and thanks in advance. <You are welcome. I have built such "shark tanks" (and more) out of pond liners (nominal 20 mil. polyethylene ("water bed") types to 32 mil reinforced, EPDM, Butyl Rubber... with good utility. The large Rubbermaid tm oval "troughs" are also very useful. A note of caution: Do make a complete, secure cover over either, as even apparently sedentary sharks can/will launch themselves out... Bob Fenner> Regards, Robert C. Taggett

Pond Advise Bob, I am assisting a landscape customer with the installation of a water feature just off of her patio. It will be concrete block with a veneer of brick to match the back wall on property line against which the pool will be built. She has about 5 goldfish and prefers no plants. We plan to use an in-line pump with a pressurized filter. A bottom drain will also be installed. Because my client wants an interior color of aqua green, we decided to make the concrete, rectangular structure and line it with a 30 ml aqua turquoise liner. Will we need to treat or paint with a rubber paint the concrete before we install the liner? Thank you for your help, Sally Rudisill, Landscape Designer, Owensboro, KY <Sally, you will not need to treat the concrete surface, however a padded underlayment is strongly recommended between the concrete and the liner to reduce the likely hood of small tears from the pressure of the occasional foot in the pond, the weight of rooted plants in pots and the very weight of the water itself. Tetra makes a commercial underlayment but many folks use heavy felt to used carpeting just the same. Best regards, Anthony Calfo in your service while Bob travels.>

Pond liner Please see our website at www.bendtarp.com for information on the nation's best pond liner values. Please contact us if you would like a color brochure with samples. <Mmm, will post your company name, link on our general, pond links pages, articles on using pond liners... and send your note along to friends/associates in the trade. Bob Fenner, WetWebMedia.com> Thank you, Bend Tarp and Liner, Inc. 1-800-280-0712 bendtarp@bendcable.com

PVC liners Please quote your best price for PVC liners, 20 mills thick, black color. The application is for irrigation canals. <Gosh, haven't sold liners for ten years... Please do use your search engines with the terms, "PVC Liner"... Bob Fenner> Hatem

Repair Question (Liner Pond) Robert, This is Doug Carrion. I live in Los Angeles Ca. About 2 weeks ago I had some trees cut back on my property, only to find that one of the branches while trimming punctured the bottom of our Koi Pond.  <Yikes> I had just bought the house, so I am brand new to the world. It looks to me like it is a black liner of some sort. How would I know which material this pond is? <It may well be printed/embossed on the material itself (if you can pick enough of it up to take a look), or at least the name of the manufacturer... Likely a Tetra product, green on one side, black on the other... 32 mil PVC... EPDM and Butyl Rubber have definite feels, looks to them...> Also, for repairing, do I take the chance of melting the material if I choose the wrong patch? Well if you could point me in the right direction, I would greatly appreciate the help, Thanks Carrion <Cutting to a/the chase here, do have one/two "pond service companies" come out and bid on this repair... They should be able to detail your possibilities quickly. You can then decide to DIY or no. Not much chance of melting the material if choosing wrong patch technology though. As I say, check through the "Yellow Pages" here. Bob Fenner>

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner
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