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FAQs on Foundation Coatings, Epoxies, Chlorinated Rubber Paints, Thoroseal (tm)

Related Articles: Thoroseal Use, Pond Repair Work,

Related FAQs on Pond Repair,

Your typical pond repair nightmare.

Aquatic Gardens

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

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by Robert (Bob) Fenner

problem with leaking cistern wall      4/26/15
Hi guys! We are trying to pump all our water into one side of our cistern in the USVI so we can repair and paint one side at a time.
But the dividing wall leaks! W
e tried to use Thoro Waterplug on the leaking areas but it dissolves in water. Now we are going to try a marine underwater epoxy. Do you have any advice?
<Drain all (both sides) and keep dry before attempting this repair. Bob Fenner>

Thoroseal? Ap.  5/24/14
I'm not sure if you can help with my problem but let me give it a shot.
I'm trying to seal my 100 gallon fountain with Thoroseal, or should I say my contractor is.
<Have used this Thoro product many times>
they fully chipped the inside, then applied Thoroseal only (no acryl 60) upon drying, the vertical surfaces of the box shaped fountain formed spider cracks.
<Mmm; yes... I would have acid-washed the surface, used a binder (the white glue... oh, I see this above/below) as well as the chipping>
I asked them to wet and recoat.
they did with Thoroseal only, and it dried perfectly this time no cracks.
<Ah good>
i wait about 5 days, then filled with water for several days.
Upon draining, I noticed a bunch of spider cracks again, only on the vertical surfaces.
it's a fountain made out of concrete block, and it's sturdy.
I'm wondering why it would crack after filling, then draining. any ideas?
should I need to use acryl 60?

<Ah yes! Cheers. Bob Fenner>

G4 Pond Sealant    3/22/14
I have desperately sought for the UK product "G4 Pond Sealant" in the US.
After weeks of fruitless searching and dozens of phone calls, etc. I have gotten nowhere.
PLEASE help me. Is it sold in the U.S. ? If not, what is an equivalent product?
<Have never seen it here; though there have been quite a few "clear pond/concrete sealants" on the market over the years in the US. Am decidedly NOT a fan of these... they don't really work>
I have a brick pond that needs its grout (cement) sealed. Everywhere I ask I get hours of runaround and product recommends that don't come close to G4.
<Mmm, well; you might try Amazon.UK... they might well be able to rig some way for this product to be sent to the States. Bob Fenner>
Thank you!!.
Re: G4 Pond Sealant    3/22/14

Thank you Bob for your quick response. Apparently G4 is a moisture cured pre-propylene polyurethane.
<Yes; these have no body.... Do read here:
and the linked files above>
Three coats, etc. I'll try Amazon UK and see what happens. It is mentioned in your blog. It is the only mention I've seen in the U.S. after many hours of searching. Nobody can tell me why it isn't sold here. EPA is stricter in Europe so am pretty puzzled... I've also received the runaround from many as to other products. When you get out the magnifying glass the small print says "not for underwater use". I don't want to coat my bricks and in the meantime it's Spring here and my water plants want to get back into the empty pond.....
<Cheers, BobF>

Re: Change of Plans to Finish Pond     9/13/13
I hear concrete and mortar are toxic to fish. Would I need to seal the concrete wall with a fish safe sealant?
<... READ here:

Concrete woes     9/14/13
I was told the concrete wall I am planning for my pond will make the water more alkaline.
I plan to keep goldfish.
Would I need a chemical additive in the water to buffer it?
<... should be acid-washed as a part of the construction process...>
Or should I try a non-toxic waterproof concrete sealer?
<Could... this is all covered... on WWM
Thank you.
Are these sealant ingredients toxic to fish?    9/14/13

polyester-polymer and polyurethane
Are either of these toxic to fish?
<... depends... of and by themselves; where applied, cured properly, no.
But don't "stick" to concrete by themselves. Why don't you just search and read on WWM?

Repainting the underwater surface of a pond     7/25/12
I recently purchased a house that has an approximately 10x8 foot oval pond with a waterfall flowing into it.  The pump pulls the water from the pond up pvc and then returns through the waterfall.  The previous owners repainted the underwater surface white a couple of weeks before we purchased the house.  They used latex based Drylok.  We would like to paint the surface a darker color.  My questions are as follows: what is the best paint to use in this situation?
<A tough question to respond to w/o knowing the make up of this basin>
What are the surface prep procedures on a newly painted surface?
<Depends on the material/s used... You MUST follow these directly>
I have power washed the surface and the paint job does not look to be to even, should I get the current paint up and start with just the concrete surface.  How would I get the paint off of the concrete surface if that is the best route? 
<... Much to state. Too much w/o having you read first. Here:
and the linked files above. Bob Fenner>
Thank you for the help.
<Welcome... take your time>

question for bob fenner re Thoroseal, coloring       6/3/12
Hello Bob,
I have a question about your article on "Foundation Coatings for Water Features - Thoroseal Use in Ponds" - 
<Go ahead>
The article indicates that dyes can be added to Thoroseal.
What kind of dyes do you recommend that are fish-safe? And where can I get them?
Any of the stucco dyes will do... they're available through large hardware stores (e.g. Lowe's), and specialty contractor outlets>
The Thoroseal product sheet says 10 different landscape colors ("Thoroseal ColorPaks") can be added to the Thoroseal, but says they are only available for large orders of Thoroseal (5,000 lbs or more!)
<Yikes! Likely sold individually through "stucco" dealers... see your "Yellow Page" directories, analog or digital>
I'd appreciate any information you can give me.
Thank you very much,
<The dyes are easy to mix (by volume or weight) in w/ the Thoroseal... w/ a paddle attachment to a drill motor, or by hand/square shovel in a plastic trough or wheelbarrow. Bob Fenner>
Thank You!

Thank you very much for your expert help. Also, for your wonderful website!
<Ah, welcome. BobF>

DRYLOK To Seal A Concrete Pond? (Yes!) -- 09/13/11
<<Hey Jeff>>
I am in the process of converting a 20' X 40' swimming pool into a fish/frog pond.
The homeowner actually did this 4 years ago; we are just now making it official.
We wanted to decrease the overall size of the pond so I have installed a cinder block retaining wall and backfilled the deep end. I have read quite a bit about using DRYLOK to waterproof the wall but am not sure which of the 5 products, specifically, you recommend. http://www.ugl.com/drylokMasonry/masonryWaterproofer/latex.php. Any help or better product recommendation is appreciated.
<<Well Jeff, I can tell you I have used DRYLOK to waterproof a concrete-block pond I built in my own yard and it has performed very well. The pond was built in '98 and the sealer has performed very well. I initially used the Oil-Based DRYLOK, but took the opportunity to power-wash and recoat a few years ago during an expansion project on the pond, and used the Latex version on both the old and new surfaces. As far as durability/performance I've not noticed a difference, but the Latex sealer definitely gets the 'thumbs up' for ease of cleanup and reduction on noxious fumes. If you make sure the walls are clean (give them a good power-wash and let dry), and use a 'minimum' of two coats applied as directed (I have found that a 'stucco dash brush' works well for applying/getting the sealer in to the 'pores' of the concrete), the DRYLOK will not disappoint>>
Thanks, Jeff
<<Happy to share'¦ EricR>>

Re: 50 year old concrete goldfish and Koi pond - 8 months later 8/15/11
Good morning, Bob. Long time no talky to. I hope all is well with you.
<Yes. Thank you Shirley>
So, here I am a year later from when I first began my pond re-do journey. To update, in a nutshell - all is excellent! I used Thoroseal on the new concrete (inside the pond). That was a chore because the outdoor temperature needed to be 60º for optimum results, and it was a rainy and chilly November in Oregon. So I built an insulated "tent" over the pond and installed a heater and fan inside. I did all the work inside this cave, over a two week span, in the middle of winter. I was ever so mindful of following the Thoroseal directions to the proverbial T. I even messaged with the TS people to be sure I was doing the best I could under the wintery circumstances. The end of the TS story - I love Thoroseal! I have read other posters' comments about TS (some not so complimentary) but it worked perfect for me - but it is soooo important to NOT be in a hurry, and to follow the directions explicitly with no fudging on any steps.
<Ah yes>
So now, jump forward. Pond is full. 55-gallon bio filter and 55-gallon settling chamber is installed and working perfectly. My semi-gravity bottom drain works marvelously. I'm using a 1200 gph Mag-drive pump submersed in the settling chamber, which draws water through from the bottom drain in the pond; this water is pumped into the bottom of the bio filter, and then overflows back into the 1100 gallon pond. My home-made skimmer is a life-saver. I bought my first new Koi last weekend after waiting all summer for the sunlight to propagate the good bacteria/algae so that the pond would finally clear (with no chemicals or UV light). I am now ready to "finish" the rather unsightly top and outside portion of the pond (see attached photo).
<Vey nice covers>
I will be using either slate or quartzite 12" x 12" x 1/2" tiles for the (horizontal) top - each tile to be custom cut into mitered wedges to fit the contours of the irregularly shaped pond. Sounds daunting but I did a trial run with paper and it's easier than I anticipated to create the templates for each tile (I'll need a tile saw, of course). After the tiles are mortared into place, I will be adhering 4"-6" travertine chair rail pieces around the outside top perimeter along the edge of the tile, and then grouting all. And then I plan to use a color-tinted stucco for the outside vertical wall. A lot of work, but do-able, and I think it will be lovely. So, why email you, you ask....
What should I use for the mortar to affix the slate tile to the top, and the grout (1/4" grout lines)? Rain, of course, will be running off of this capstone and into the pond. It was suggested I use a multi-purpose mortar/grout - and if I did, could I use an acrylic additive as the wetting agent to make the mortar more stable/harder/better adhering/safer for fish?
<Yes to these>
Can I use plastic cement (if I can find it) for mortar and grout? What would you suggest?
<I would use the multi-purpose... mixed w/ a blending bar, attached to a variable speed drill... in batches... with the additive>
Oh, and then there is the final landscaping.
I love my 50 year old concrete pond! I love my bio filter and settling chamber design. It is practically maintenance free, and the fish are thriving.
Thank you for all your previous help. I hope you have had a marvelous summer!
Shirley in Oregon.
<Thank you; BobF about done in Maine>
ps. The image you uploaded onto your web page, that I sent you of my filter design, is kind of hard to make out - somehow there are two images there, one on top of the other, making it hard to tell what is what. Just thought I would mention it in case somebody wanted to consider a similar design for their project.

Application of Thoroseal 7/22/11
WWM Crew,
I have built my first concrete Koi pond and I'm in need of some guidance about the use of Thoroseal. This is a 4,000 gallon pond. To seal the concrete I opted to use Thoroseal for the ease of application and the cost effectiveness. Plus I don't mind the gray concrete look as it will gradually darken over time.
<Agreed... though coloring can be added... all turns darkish over time>
I applied two coats back to back waiting for the first to harden up (maybe 30 minutes)
before applying the second. I know the instructions say to apply the second coat after 12 hour cure time, but applying back to back allows for the two coats to form one thick coat (and the pond does not leak).
<But disallows the first coat to breath, cure>
Anyway, after applying Thoroseal and filling up the pond
<Wait... how long did you allow the coating to dry/cure?>
the PH level was up over 9, more likely over 10 (well water is 7.2 used to fill up the pond). I read some different opinions online and decided to do the following:
1) drain the pond
2) power washed and pumped out every last drop of water
<Careful on the power wash... and I would have done the acid was with new water in the pond>
3) muriatic acid wash (scrubbed the entire pond with a 1 to 4 acid to water solution - 3 times)
4) power washed and pumped out every last drop of water
3) filled pond back up.
I was hoping that after the excessive acid washing that upon filling the pond back up I would be able to stabilize the PH closer to the 8 mark.
This was not successful. After a day or two, the pond PH shot back up to over 9. My next solution was to keep adding muriatic acid to the pond until the PH stabilized around 5. If it stabilized then my assumption was that the leaching had stopped. Once it stabilized I was going to drain and then refill and be ready for the fishies. Well, it never stabilized. I added acid every day or so for 4 to 5 days and kept the PH real low, but as soon as I stopped adding acid then it shot back up.
<Drain and let this pond sit dry for a week or more>
After adding this much acid I noticed that at the water line and below it was much lighter in color than above water line. I rubbed the side of the pond with my hand and clouds of gray dust came off the wall surface. So, I assumed I added so much acid that it deteriorated the Thoroseal coating.
So now I'm kind of lost and can't find the info I need or want to read.
<... I'd contact Thoro here... The first giant mistake was not allowing the first coat to cure before applying the second... Next, how long did you leave the pond to dry overall? Next, power washing is a no-no w/ pond coatings... Acid washing should be done per the SOP posted on WWM (an olde article by myself), brushing or mopping on the acid-water mixture... maybe with a soap added to knock down fumes>
As a contractor, I do think that Thoroseal would be a great product because of it's cost effectiveness and ease of application when sealing a concrete pond. I want to continue to build more concrete waterscapes, but also want to find the best water proofer with the least amount of headache. It's just not realistic to have to drain a large pond 3 or 4 times, and acid wash, and do all that to get the Ph to an appropriate level for fish to thrive.
With that all said and driving myself nuts trying to find the best solution, I tried to remember back when I applied the Thoroseal which was about 2 months ago. I do remember the next day it had rained. I was worried about this but at the same time not too concerned. I checked the next morning and the Thoroseal was rock hard. As a mason, I work with cement and mortar all the time and know that you have to keep it hydrated to allow for the best cure.
<Yes, but just moist>
But with Thoroseal being a cement based product I assumed that it would be all right for the rain water to sit in there to help it cure.
I'm draining the pond now and when I rub my hand on the sidewalls of the pond I get concrete residue on my hand. And as I mentioned earlier the walls are turning a whitish color but the brush marks from application of the Thoroseal are still there.
So, I guess my questions are as follows:
1) Was I not able to maintain the appropriate Ph because of the original incorrect application?
Did me not allowing a full 3-4 day cure time ruin the application?
<Likely so>
2) If applied correctly, how much acid washing does one really have to do to then fill a pond up and be ready for fish?
<Very little in my experience. I don't know if Thoro has changed their formulation/s, but we used to just fill and drain once. Not acid-wash at all>
3) Are there other cost comparable waterproofing solutions to Thoroseal?
I been researching everything from Sani-Tred to Dry-Lock to Pond-Armor.
They all sound great (and expensive), but it seems that there are a lot of people on the web that swear by Thoroseal.
<I have tried/used Dry-Lok's products. These are also "real", useful>
In closing, and sorry for the rambling, I really do WANT to like the Thoroseal product. It's very easy to work with and cheap compared to other products. I basically want you to tell me it was an application error and when I reapply another coat of Thoroseal, then mild acid wash it, it will be ready to be fish safe.
Thank you very much for your time.
Brian M*c*Kie
<Welcome. Again, if you were my customer, I'd be calling Thoro re your experience, re-doing the work per their spec.s for application. Bob Fenner>
Re: Application of Thoroseal 7/23/11
WOW! I believe that was one of the quickest response times ever recorded.
<Sometimes that bro is on!>
Thank you Bob for your input. It is very much appreciated.
<Certainly welcome Bri>
I anticipated having to re-do the Thoroseal coating, just wanted to be sure that was my next step. I will wait the time required between coats this time. I took the advice from another pond guru who has always done the consecutive coats with success. It probably didn't work in my case because
of the rain the next day which I decided to leave on the floor of the pond.
Oh well, you live and you learn. As this is my first pond and this was my only set back I'm pretty happy with the end results.
Also, you say to wait a week or so after draining. Is this to allow the pond walls and floor to fully dry or some other reason?
<The first; to allow to dry thoroughly>
I could torch dry everything to speed up the process?
<Mmm, don't know. I wouldn't do this... the finish here, like concretes, is a crystalline solid, with some water trapped at interstices... the real reason for (slow) curing... Quickly drying it out would weaken this lattice>
I'm anxious to get this water chem. right and get some Koi in the pond.
<Heeeee! Of all the many worthwhile lessons that keeping ornamental aquatics can teach us, patience is likely the best lesson>
Well, thanks again and have a great weekend!
Brian M*c*Kie
<Thanks. Am up in Seattle, giving a couple of talks. Cheers, BobF>
Re: Application of Thoroseal 8/15/11

Hi Bob,
I hope all is well. I'm experiencing issues with the Thoroseal product.
If you can recall I had originally applied the Thoroseal wrong. This was per guidance from another experienced contractor who uses it as a pond sealant and has done over 1,800 ponds.
So, per your guidance I re-applied. The first coat had a full 24 hours cure time. The second coat had 24 hours cure time then it rained.
I had covered the pond but water still got in. I then vacuumed this out as soon as possible and let sit dry for 2 days or so.
<I'd leave it for a week>
After waiting about a week after the first coat and subsequent second coat I began the process of mild acid washing. I did this for two consecutive days. We have been getting a lot of rain here in the Northeast so today (a week after 2nd Thoroseal coat was applied) there was about 4 inches of water in the pond. Out of curiosity I checked the pH of the water in there and it is at 9.5 or greater. This could be from residual residue after the acid washing but don't think that would be it as I really vacuumed out every last drop.
So, I'm lost now. I don't want to fill up the pond only to have to drain it again to try and get the pH at the appropriate level. I could fill up, put a pond starter in there and get some plants in there to help stabilize the pH. Then throw some goldfish in and see if they'll survive, but if this doesn't work either then I'm back to the original problem. This would be leaching of the Thoroseal. Also, in doing a pond in the future this is way to time consuming before fish can be introduced.
What would you recommend?
<I'd fill it, leave it for a week... see what the pH is at that time... if near/er 8... add some live plants... If much more than eight, drain it, refill, wait another week>
Could it be something else? It is a concrete block pond on a 6" reinforced slab, then coated with mortar on the vertical sides and the bottom. Thoroseal has been applied twice now. There are no leaks just a pH issue. As I've said before I really want to like the Thoroseal product because of its cost and ease of applying but I'm beginning to become skeptical. Please help!
Thank you in advance.
<Welcome. BobF>

I read Bob Fenner's article about Thoroseal use in Fish pond.
Here is the Question: What kind of dye could be used mixed with Thoroseal, non toxic for Koi fish?
Thank you
Alec Popovici
<There is a large selection of mineral dyes for such... see your stucco dealer, or large warehouse store (Home Depot, Lowe's) re. 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>

Rubr-coat 57 9/20/10
Have you ever heard of this product
<Mmm, no>
and if so, can it be used to seal a small cement pond?
<I am hesitant to respond to the affirmative. Not much stated in the use sheet:
Nor see in the co.s FAQs offerings anything re permanent underwater use, but the long cure time is indicative of something that should not be>
I plan to add a few fish to the pond and my dogs use the pond for their drinking water so toxicity is a big concern. Thanks for your help.
<I would be writing the manufacturer directly re... and getting their assurance re this use, toxicity in writing as well. Bob Fenner>

Leaking pond made of concrete sections 4/29/10
Our 9' diameter pond was constructed of 6 concrete sidewall sections, all of which are cemented together and on top of a concrete deck (base). To stop leakage at the concrete-grouted seams where the sections abut each other and between the sections and the concrete base, I have successfully used Marine GOOP, a clear and goopy sealer
applied from a tube and smeared over the leaking surfaces.
<Am familiar... is "amazing">
After 10 years of mostly leak free operation, the pond is now leaking rapidly and re-application of GOOP has not solved the problem. I have removed the newly applied GOOP using acetone but have not yet applied it a second time. The seams are flush with the side sections and can't easily be caulked. The side sections are made to look old and are impregnated with a color stain. Using a liner or applying an overall coating is not acceptable. Do you have any other suggestions for sealing the seams?
<Mmm... there may be a elastomeric product that will work here... The seams will have to be meticulously clean and dry... I'll plug my fave line: Thoro: http://www.thoroproducts.com/
and read here re use:
and the linked files above. Bob Fenner>
Re: Leaking pond made of concrete sections
Thanks for the information.
<Welcome. BobF, who's been there, done this...>

Koi Pond Leak ('Drylok' Waterproof Coating) -- 04/22/10
Hi guys!
<<Hey Jim>>
Just discovered your website.
I have a Koi pond about 14 feet by 14 feet and about 3 feet deep.
It came with the house when I purchased it 10 years ago. In the last 6 - 8 months started having a leak and filling it with water every couple of days. Today I put a coat of Drylok all over the pond and tomorrow will put a second coat. How soon can I return my fish to the pond after drying?
<<I use this same product to waterproof my own 'concrete block built' pond 'for twelve years now 'and again with a recent expansion 'it works great! Being a cement-based product, the coating will raise the pH of the pond water initially. It's best to fill the pond, let it set (empty of fishes and plants) for a day, drain and refill, let set another day, then drain and refill again. In my experience, this is enough to render the pond safe for Koi and Goldfish. Cheers, EricR>>
Re: Koi Pond Leak ('Drylok' Waterproof Coating) -- 04/23/10
<<Hiya Jim>>
I appreciate the fast response.
<<Quite welcome>>
Thanks for the re-assurance that using Drylok was a good solution.
<<It has served me well...though it has just occurred to me that you had a 'leak' before resorting to the Drylok. I do hope you found and patched this if it was more than just a matter of 'permeation' through the pond walls as Drylok is not great at filling cracks and such (again, I speak from experience)'¦but does indeed excel at waterproofing 'sound' cement/concrete surfaces>>
Very nice to know that an expert and someone who loves their fish like my wife and I do can lend some advice and knowledge.
<<Mmm, I view myself more a 'student of the hobby' than any kind of 'expert''¦but I'm happy to share my experience and opinions>>
A follow up question.
Because the pond is rather large and refilling it twice can use a lot of water. We live in Georgia where water restrictions can be harsh and local governments can and do sometimes monitor water usage and will issue very stiff fines for excess consumption.
<<Understood (I live in SC)>>
What can I use to cut or reduce the pH level in the pond?
<<Well Jim, nothing beats the good ole' soak-rinse-repeat 'but an alternative would be to wash the Drylok coated surfaces with a weak acid solution, say1-part Acetic Acid (White Vinegar) to 3-parts water, and then wash down/rinse with a garden hose and remove the waste water. It's hard to say for sure but two such treatments, allowing the coating to dry overnight between treatments, will probably render the pond safe for your fish 'do test the pH of the water before introducing them, to be sure. Though more labor intensive, this process should save considerably on the amount of water used versus filling and draining the pond a couple times>>
<<Good luck!'¦ EricR>>
R2: Koi Pond Leak ('Drylok' Waterproof Coating) -- 04/29/10
Hi Eric,
<<Hey Jim>>
Thanks for the tips on my Koi pond last week as you can see below.
<<Quite welcome>>
Yes I did go through the pond and seal anything that looked like a crack and the pond is holding water so far.
<<Ah, excellent'¦ As I stated, the Drylok is great for waterproofing a sound/solid concrete surface but is not meant for and does not 'seal' cracks>>
The important thing is that so far I got a "two thumbs up" from my wife.
Another question, the pond is developing foam?
<<Mmm, yes 'another argument for the fill/flush/fill/flush method of curing the Drylok'¦and particularly not unexpected if you used the 'vinegar wash' method, described in our previous exchange, to neutralize the caustic effects of the cement in the Drylok>>
I added a third pump that acts as a fountain and the water is collecting and forming foam? What is causing it and more importantly how do I get rid of it?
<<Some foam initially is to be expected'¦ In your case, the foam is probably from a reaction between residual vinegar used in the wash, and carbonates in the cement used in the manufacture of the Drylok'¦and/or it may be caused by a high concentration of dissolved solids in the water resulting from not totally flushing all the waste-water after the wash. Either way it's likely harmless. A water change may take care of it, though as I recall, this alone is an issue for you. You can try skimming it out and waiting a few days to see if it subsides (it looks like we have some rain headed our way [GA/SC] that may also help you out here), or you can try a pond defoamer like 'Microbe-Lift Defoamer'>>
<<Regards'¦ EricR>>
R3: Koi Pond Leak ('Drylok' Waterproof Coating) -- 04/30/10

You are the BEST!
<<Thank you!>>
Thanks for the tips and being willing to share the knowledge. Whenever possible I will ALWAYS pay it forward and give you credit.
<<It has been a pleasure sharing, Jim. Please do keep me posted and maybe send along a pic or two once the pond is restocked and in balance. Cheers'¦ Eric Russell>>

Poly-urea. Pond coatings 3/10/10
I have a small Koi pond with 3 Koi that don't seem to appreciate the fact that it is small -- they keep growing!
I've tried explaining it to them that remaining small would suit the pond better but they seem adamant to continue growing, so I have to rebuild and expand/deepen the pond.
<A project for sure>
It's currently poured concrete painted with an epoxy paint. I'm happy with the design and serviceability, I just wish I'd made it much deeper. What I would like to do is saw the concrete about 6 inches from the surface edge and excavate the bottom in order to make the entire pond deeper, while at the same time expanding one end to lengthen the entire pond.
I was thinking that polyurea
<Mmm, maybe: http://en.wikipedia.org/wiki/Polyurea>
would be the best coating rather than the time and expense of epoxy painting, but I'm getting mixed information about this coating from various sources and web sites. The coating is ready for fish within hours of spraying, but if I excavate and pour cement, the cement would have to cure for several weeks
before they could spray polyurea. But
then if I excavate and lay cinderblock, they could spray that afternoon?
<Mmm, I'd wait about the same cure time for both... likely a few days if the weather is moderate>
The cinder block still has mortar, doesn't it?
<It is... and you'd be using mortar to cement all-together... and likely filling at least half the cells (I'd fill all) with concrete...>
What about pouring cement and then covering the cement with geotextiles?
<Can be done... even tile>
My question is really about how I can circumvent any long term curing process during which my Koi have to stay at their mother's house or something.
<I'd get, set up a "kiddie pool" (in a weather-protected area) of size, move all the existing water into it... and monitor your water quality, Koi there during the re-construction and break-in period... Run filtration/circulation/aeration there...>
If I can dig a bare hole, line it with geotex and spray that afternoon ... why can't the cement cure for 24 hours, be covered with the same cloth & then sprayed?
<I'd wait a few days... Bob Fenner>

Fishpond, rock/coloring 10/12/09
I have built a concrete lined fishpond and have sealed the concrete to make it waterproof by fibreglassing the surface. It holds water beautifully without leaks but does not look very natural as the fibreglass resin was
grey in colour. I want to make it look like natural rock (sandstone) and have thought of the following method:
Paint the surface with waterproof paint and then before the paint dries sprinkle it with cement colouring oxides of the right shades.
<Can be done>
My question is will the oxides be toxic to fish?
<None are toxic that I'm aware of. Our company used such to dye mortars in making artificial rockwork for years>
Please respond as soon as possible.
Kind regards
Selwyn Adelson
<Bob Fenner>

Re: Fishpond, coloring oxides 10/14/09
Dear Bob,
Thanks for your prompt response - it was much appreciated.
Kind regards
Selwyn Adelson
<Welcome Selwyn. I have used literally thousands of pounds of these coloring oxides in making artificial rock and coloring cementaceous materials in ponds, biological and not. Cheers, BobF>

Re: Fishpond 10/14/09
Dear Bob,
I have now used the oxides sprinkled onto wet pond paint and before the paint dried it started raining. I cursed my luck but in fact it worked out very well as the rainwater blended the colours into each other and now that it has dried it looks stunning - just like natural rock with a subtle gradation of colour.
Thanks for your help.
All the best
<Thank you my friend. BobF>

Does this product work? Liner pond, repair/coating 9/21/09
I have a fish pond that is probably 35 ft. long stream with 2 6ft across ponds at both ends..It leaked slowly for years so i Put in the rubber lining. and it didn't seem to work.
so I am slowly emptying all my water out since I lost all my fish to Raccoon ..GRRR
I want to coat & seal it hopefully permanently any suggestions you can give me i would appreciate..I found this company Sani Tred and it sounds perfect, so I wanted to know if have heard anything about it for recoating my pond.
here is the site:
Charr Cook
Napa CA
<Have never used it, but reading over their site, it does look like it will work... I take it the space under your liner is pretty well compacted by now. Bob Fenner>

Re: Does this product work? 9/22/09
Thank You for answering me. Yes it is concrete under the liner an it was put in 15 yrs ago.
so I will try it and let you know..might be next year though..
Thanks again
Charr Cook
<Thank you Charr. BobF>

Elastomeric Stretching System(s) 7/30/09
Greetings Bob, after following your FAQ's on Repairing Concrete Water Features and other articles at WWM for my first "crack" at repairing my 20+ year-old Koi pond here in Tempe, Arizona, I was pleased and thankful for the information and suggestions you have provided. However, I have learned I probably need to go with a elastomeric repair system for my next repair due to the age and severity of the cracks that have developed (or at least I'm willing to try). Can you suggest a few companies/product lines that I can research/obtain readily here in Arizona?
<Unfortunately no... have just been out of that business for too long.
However, I do know how one/I'd proceed in searching. I'd look for a nearby Koi and water garden club, contact them and ask whom they'd suggest... AND interview folks who have adds in the "Yellow Pages" pulp and e-versions>
I've had three pond companies bid on the repair(s) that resulted in various solutions and options and $$$ --am I willing to do the work myself with if pointed in the right direction... Oh, and my ability and perseverance is and has remained "upbeat".
Thanks, Robert
<Oh! Then I'd search on the Net re the materials (and possibly tools) "they" listed and look into purchasing these directly. If folks don't stock, likely they can be ordered, drop-shipped to a pool gear supplier in your region for pick-up.
Bob Fenner>

Thoroseal Products -- 4/30/09
Thank you for your informative site.
I've been trying to hunt down Thoroseal in the Santa Barbara area and keep being offered alternative products. One place that did sell me Thoroseal substituted Thoroseal Foundation Coating and I didn't notice until I got the bags home. The website of Thoro - Products says that only Thoroseal has been approved for cisterns. Does that mean that conversely it would be unwise to use Thoroseal foundation coat to waterproof my fish pond using the methods you outline?
<Nope. Is fine to use as indicated>
What about these other brands that everyone else carries and want to sell me instead?
<There are some other mighty fine lines... some are quite similar in formulation, applications...>
Thank you for your help.
<Welcome. Bob Fenner>

Pond sealing, reading 4/19/09
I just found your web site today and I have to say it's been very helpful.
I've read the other questions you've been asked on sealing ponds etc, and I have a question.?I used pond shield epoxy on my concrete block pond (a lot of it) it has never sealed fully.
<A common problem, issue with these products, these applications>
I can't find the holes it must be leaking out of and to tell you? the truth I'm feed up with the stuff. Is there anything I can use to cover it Thoroseal, CR paints, can I have use quick set cement over it to give my self a new base to work with?
<All posted...>
I'm almost tempted to buy a pond liner and just use that.
<Another alternative... also covered...>
Thank you so much for your time.
Blake Hazen
<Please re-read here:
Bob Fenner>

Having an issue sealing our pond... please help! 4/10/09
Hello Crew!
I wrote Bob Fenner quite a few months ago (when our Red Tailed Catfish was much smaller!) regarding a plan for an outdoor pond to house him. After more research, and much, much more thought, my husband and I chose to build the pond indoors (in our bedroom, no less).
We have had a mason build the pond, which is approximately 800 gallons in the main part, with a 100 gallon 'filter'. The filter is just part of the pond with a lower wall of cinderblocks separating it, so that a waterfall occurs when water is pumped from one end, through pvc pipes that are running at the bottom of the pond, through holes in the wall, to the other side in the filter. We used Pond Shield, which is an epoxy coating.
<Mmm... these epoxies have no real "stretch" or body... the basin, material they are applied to has to be very stable, cured...>
We have applied, now, six kits to this pond. Each kit is supposed to cover 60 square feet, and the pond is only 11X8X3 and a 1/2. The filter part is leaking. The mason did 'parge' (his term) the pond, meaning that he took a thin-set concrete and covered the cinderblock shell on the inside.
After the leaks, we examined the walls, and saw tiny holes in the filter part. It is a small area, only sixteen inches wide, and I can imagine it was difficult for him to get it really smooth. We have considered purchasing more epoxy, but are worried that we'll never really 'fill' these holes.
<I agree...>
Is there some type of putty or silicone or something that we could use?
<Mmm, really... I would reseal all with a cementaceous based coating... Thoro- material or equivalent. Please read here re:
and especially the linked FAQs files above>
The holes that we suspect are the issue are not more than a millimeter across, and could easily be filled with something, but we're not sure what would work long-term. Is there something we could coat the entire filter area with to ensure no leakage?
<Yes... and I'd go ahead and coat all the inside surface>
We really want this pond to work, as we've put so much money into it already, and Guido (Catfish) continues to grow (he's now at sixteen inches)! He is in a 125 with a sump, by himself, so he is okay for now, but I hope you have some ideas for us. Thank you.
<Read on! Bob Fenner>

Re: Having an issue sealing our pond... please help! 4/10/09
Hello Bob--
I have examined the links you provided on ThoroSeal products, as well information on their website. However, I think there may be an issue when it comes to applying this product to our pond surface.
The surface is already covered in epoxy, and the company's website specifies that the product "may not be applied to painted surfaces".
<This is... more of an "exemption from liability" statement than likely factual...>
Unfortunately, it looks like we may be stuck with the epoxy, now that the epoxy is on the pond. Do you agree?
<No... there are ways of prep'ing the current surface such that most any new material, coating may be tried... And there are other options... If you would take the time, do look into CR (chlorinated rubber) "paints" (for pools), other "slab" water proofing applications... I just do NOT trust epoxies in such settings. They have too often not proved long-lasting>
Thanks for your quick reply, and a big thank you to all of the crew for this great, informative site.
<Welcome, and please do keep me/us informed of your experiences here. Bob Fenner>

Pond Armor -- Attn: Bob Fenner 4/18/09
Hi Bob--
I am writing to update you on the pond we've built in our bedroom that we chose to use a product called Pond Armor to seal. I called the company after we purchased two more kits, but before we applied them, to find out why we were having so much trouble. I was asked whether or not we were using denatured alcohol. I replied that no, we were not, because the reason explained in the literature included with the product for its use was to make the product workable for longer, which we weren't having a problem with. The representative then went on to explain that tiny pinholes are created in the epoxy due to gas escaping from the concrete during the curing process, and if denatured alcohol isn't used, these pinholes will never close back up,
because the product will be too close to curing. I am appalled. This company is withholding information from the consumer, thereby creating a situation where the consumer has to keep trying 'one more time'. I will not try one more time. I do not trust this company or its products. I think we're just going to go with a liner, and in the meantime, I have written to this company in hopes of getting a refund for the money we threw away on this product. So, to close, NEVER USE POND ARMOR! I hope this saves someone else a lot of money. Thanks for your help.
<Thank you for this first hand testimonial. Bob Fenner>

Re: Leaky Koi Pond, fixed, now high Alk. from Thoroseal 2/13/09 Thank you for your help earlier. I now have a leak-proof pond. The ThoroSeal finish was really helpful. <Thoro does have some very useful products for sure> I am now having problems controlling the pH which, uncontrolled, will drift up to >8.5 in 48 hours. <No worries... allow to "soak" for a few days, drain, perhaps do a dilute acid-wash (see WWM re), and re-fill> The whole pond is ThoroSealed and I use only rain water for filling. The rainwater's pH is 7.5. I have nothing else in the pond likely to affect pH I noted that on the MSDS for ThoroSeal it says that it is alkaline, but does not say how much. <Yes... tis the alkalinity in this product that has bolstered the pH here> Does the alkalinity leech out and finally go away. <Yes> Is there anything else I can do other than keep adding acid? <Mmm, time going by...> Thanks. Jack <Please read here: http://www.wetwebmedia.com/PondSubWebIndex/acidblchpds.htm and the linked FAQs files above. Bob Fenner>

Staining a new Gunite pond 10/9/08 Dear Crew, <Dana> I looked through your excellent site but couldn't find a reference on how to stain a new Gunite pond easily or inexpensively. <Mmm... this is almost always done by applying a "cement/plaster coat" that is colored itself... over the Gunite shell... there are "jobs" where the Gunite itself is pretty much waterproof... but not always. I have seen rebar rust through... over time, and this is very difficult to mask over after... Applying one of various "pool paints" (epoxies, "rubber", et al.) can be very expensive, not very wearing/lasting... and cementaceous materials (e.g. Thoroseal et al.) may also not be long-term successful...> My husband estimates its size at 10,000 sq. ft. <Good-sized> They installed a liner and pad, <Ah, good> did the reinforcing and sprayed on the Gunite, and it looks great except it's very light and bright and needs help to blend into the red and brown dirt we have around here, especially when the level goes down, as it does every summer. <Mmmm...> Before the pond was "improved", the yerba Buena would bloom around the edges as it dried out, and it wouldn't look so bad. <I see> We need an inexpensive option, if there is one, as the pond has come in way over budget. Can we use black mason's stain or iron sulfate? <You could... along with "biological staining" this might well "do it"> I read that the iron sulfate is cheap. <Can be, yes> We do plan to put some fish in the pond but no plants as our consultant says they will cause leaks. <?... what sort of plants? None should be able to penetrate the Gunite> We built the pond for late season landscape watering, as we have no rain for 90-120 days most summers, and the well and cistern can't do it all. So the water level will go down as we pump it out in late summer, and it would look so much better if it wasn't just pale gray. It's fairly steep, as well. <Do take care that this area is safe... fenced to prevent children, stray animals from drowning> The water will be used for swimming and to water plants, so water quality is somewhat important. <... I would like to know a bit more re the filtration to be applied here... Usually there is an either/or choice to be made whether such bodies of water will be ornamental OR swimming "holes"... there are some health issues...> We mostly need to stain the top portion that shows all the time, so we don't have to do the whole thing. <Understood> I'm hoping you have an easy answer, as this will be DIY. Also, does the surface have to be sealed after staining? <Mmm, not likely. Depending on the method used ("cement plaster coating", staining, painting/coating...) Another big expense we'd like to avoid, obviously, but not if the stain comes right off. We have to do it before the rains start and the pond fills up, which is pretty soon, here in the Northwest. Could you mention suppliers for the stain, also, if you come up with some ideas? We live in Eugene, OR, and although it's not small, it's not real big either. Thanks so much for your help. Sincerely, Dana Hansler <Well... I REALLY wish I could have suggested applying a colored shotcrete shell (roughly... with small aggregate, maybe 3/8" nominal) over the Gunite along the entire edge (when it was new) and roughly tooling this to make it look more "natural"... this would allow for a better look for sure, and make it easier for life to get in and out (do take care when it is filled... treacherously slippery)... At this juncture, I would go a Thoro product route myself. Bob Fenner>

Benjamin Moore Paint for a new Concrete Koi Pool? 7/25/08 I live in the Virgin Islands where getting ANYTHING except a sun tan is a hassle. <Heee! Know what you mean> B Moore makes a chlorinated rubber underwater paint which is available here. But unlike numerous other manufacturers BM does not specifically say that the paint is OK for fish ponds. <Mmm, have used a few of these CR paints over the years... they are fine, once cured, in terms of non-toxicity... BUT are the Dickens to get to adhere properly on anything but the most ideal surfaces... New, absolutely clean, good weather...> The other manufacturers, like Kronalux, say their paint is OK for fish ponds but not for "painting containers used for water or food". <A wise disclaimer> Do you think that I will be OK to use the BM product? Getting an alternative will take weeks, but I obviously want to get it correct. <Mmm... I really want to encourage you to look into other materials for pond coating... rubber paints just don't last in these applications, and they really "look funky" in a few weeks time... with algae et al. growing on them> I've scoured you wonderful web site and have noted your existing recommendations. My problem is that I can't just go down the street to the paint store and pick what I want off the shelf. Thanks, Jack <I'd have some "Thoro" product and color shipped over from Florida... Bob Fenner> Re: Benjamin Moore Paint for a new Concrete Koi Pool? -- 07/25/08 Thank you very much indeed for your advise. I really appreciate it. Jack <Welcome my friend. Please do send along pix of the finished project if you remember. Cheers, BobF>

Thoro Paint For Koi Pond in Paradise. -- 7/30/08 Hi! Bob, <Jack> I've been away for a few days but thanks again for your advice. Which Thoro product do you actually recommend. Thoroseal is used here for cisterns and is available. <This is what I would... and have used many tons of> The Thoro data on their website seems to recommend it for ponds but I did not see any specific mention of fish. I thought I'd just check in with you one more time to be sure, as this adventure is a first for me and I don't want a great looking pond with dead fish!!! The copy addressee is Don Dewerd our contractor. Thanks again, Jack <Welcome. BobF>

This n' That... Gunite, waterproofing ponds, surrounds... 7/18/08 I am so glad you guys are there. We had a pond Gunited 3 weeks ago, it measures 33' long 22' wide 3+' deep. Around the whole perimeter is a shelf for boulders, rocks, plants, safety shelf. <Mmmm> I do not know of another way to seal this other than plaster, <Does need to be sealed... Gunite is NOT water proof> clear to the top edge, the boulders will set down in the water about 4" on this shelf. What do I seal the top shelf with? <Likely more "cement plaster" with color/oxide...> What about clear Herco rubber? <Not if I were doing it... expensive, not really an appropriate application> After whatever I uses dries I figured mixing mortar or cement to fill in the back of the shelf, <Well... I do wish we were starting from "go" here... but as the shell is already shot out... I would cement plaster (or otherwise... see WWM re... Thoro et al. products) seal the entire basin, including the "bench", then place the rocks (I'd use bits, swatches of "old carpet" to set them on... over the plaster... and seal about these in turn... and behind them a bit, to over the real water level of the berm... I do encourage you to get/use a water level... to assure this> where the void would be, set the boulders that varies 1' to 2' boulders wide on this shelf, mortar in-between the boulders and seal this with the clear Herco? <Mmm, no... won't work, or last> I am also wondering how to leach out the lime in the plaster? <No big deal... easily done over time, or through acid-washing... again see WWM re> No hurry for fish. I have 3 sequence pumps <Ahh! Very good products> pulling water from the 3-3" bottom drains, from the pumps the water is pushed up hill 25 feet away, up 12' to the 3- 15' long 3' wide 2+ feet deep biological filters, <Nice> lave rock, white filter media, brushed, returning down the 12 tall water fall. I have u.v.s for this pond, taking into consideration this pond will be in direct sunlight 6 hours a day. <Do get, record values for pH, alkalinity, perhaps DO and RedOx... and time of day readings were taken> I am also concerned about the water heating up, I am thinking of the plaster (white) coloring <? Don't do this... it won't stay white anyway... do mix some color in with this... even something other than sharp sand... e.g. crushed rock... to make stepping into the basin less treacherous... and to promote useful growth of micro-life there> it with a tint of blue/gray but keeping it on the lighter side. <Nah... again, won't stay this lighter color for any period of time... choose "something more natural"... a brown or tan perhaps> I am also concerned about algae bloom. My initial fill of water will be from filtered water, the water running through solar salt, we live in the country our water from the well has a LOT of iron in it, my neighbor is going to fill this from their system, us being concerned about to much draw on the pump in the well. <Mmm... a bunch to state... but I'd be looking into "bio-amelioration" here... using some, likely floating and "grass" plants to remove a good deal of the ferrous, ongoing available nutrient to the algae, harvesting (removing) this periodically during the sunnier, warmer months> to keep this pond topped off, I will be using a float valve, the water will be coming from our filtered water system, the water running through solar or potassium first. I do need to get the lime out of this plaster, what do you rec for doing this? (vinegar? how much) sealing the top edge of the pond to set the boulders on and topping the pond off with our systems water? thank you very much Judy <These and many more important issues are covered in a general sense in articles, FAQs files archived here: http://wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm Learn to/use the search tool (linked on the left shared border) and/or indices. Feel free to write me re specifics. Bob Fenner>

Cheap pond coatings 3/12/08 Mr. Fenner, I'm looking for a cheap pond coating. I've looked at roof coatings. (asphalt emulsion, acrylic elastomeric, etc) Are these products safe to use in the pond? <Mmm, yes... all are... once totally cured... therein lies the real issue... Some of these are not easily... totally... cured> Will they leach chemicals into the water? <The asphalt-based ones, yes... to degrees... depending on... how "cured", batch, product type...> What would you suggest? I don't want to go spend lots of money on other coatings if asphalt emulsion will do the job for less than 1/2 the price. <Mmm, do you need a coating at all? What for? What are your basin/s composed of?> Is there a paint I could put over the emulsion to avoid leaching? <None that I know of, no> Any suggestions would be great. <Read here: http://wetwebmedia.com/PondSubWebIndex/thoroselart.htm and the linked files above. Bob Fenner>

Fish safe pond coatings 2/13/08 Hi, My question is about asphalt emulsion use for a pond (concrete) liner/coating. Is it safe to use? If so, what type do I need? Henry's 107, 201, fibered, nonfibered, any brand, etc? I've heard that some folks have had success with Drylok. Please give me your thoughts on the subject. Thanks so much. Simon <Years back we used a great deal of asphalt emulsion of the Henry's and Marvin's brands... and IF cured thoroughly rarely had troubles. However, nowadays I urge caution re their use... as these products have proven very inconsistent... and am worried re their possible failure and toxicity. Please read here re pond coatings: http://wetwebmedia.com/PondSubWebIndex/thoroselart.htm and the linked files above. Bob Fenner>

Leaky pool, convert to pond Mr. Fenner, We have bought a 70 yr. old property that has a rectangular pool (15' x 25') at least that old. It is a concrete pool that was deep enough to have had a high dive and was filled in with additional concrete years ago. It is now leaking about 3 feet down on the sides. It has been painted before with Pool Paint. I am tired of dealing with a pool and would much rather convert it into a pond, very natural and with an Asian look. Can I use a liquid pond liner, rubber paint or some sort of water proofer? <Yes> I have read about Neoprene Paint and DryLok Waterproofing. <The former is ghastly... the latter much better> I have also looked into fabric liners. We don't want to simply fill it, just repair it to be water-tight and add some fish. Do you have any suggestions for me? Susan Morris <I do. Please read here: http://www.wetwebmedia.com/PondSubWebIndex/thoroselart.htm and the linked files above. Bob Fenner>

Pond wall sealer 12/12/07 Hi: I have a pond that has been excavated out of coral rock in Homestead, Florida. <Ahh, will be visiting a friend there in a couple of weeks. He has many such ponds... two cichlid farms...> This pond is 140' long and 80' wide with two islands inside. As you know the coral rock is not able to contain water and has large holes and cracks. <Yes> Is there a substance I can spray on the walls to contain the water inside. <Mmm... possibly> I can not spray the bottom of the pond as I am in the water table. So my pond is currently partially full but can not be filled further unless I seal the upper portions of the walls. Most substances are designed to go over concrete. What can I do. I have heard someone mention fiber coating. where can I find this. <Mmm, not fiber-coating... You could fit, have fitted, a liner here... There are other techniques... even just constantly filling, allowing to percolate... What is it you intend to do with this basin? If it were me/mine, I'd have some contractors (see the phone directory, under "ponds", "landscape") come on out, bid on what they advise might be done here... In the meanwhile, please read here: http://www.wetwebmedia.com/PondSubWebIndex/pdconst.htm and the linked files above. Bob Fenner> David

Pool to Pond Conversion, sealing the old plaster 12/5/07 Dear Bob: I have an old pool that came with a house that I just purchased. I am trying to convert it into a fish pond. The pool, as far as I know is solid and does not leak. The plaster is old and I plan to knock off any loose stuff and put a color sealant on the entire surface. <Do take care here... eye protection, heavy gloves, Levi-type pants... the cement plaster is sharp! And heavy at times> Unfortunately, I verified with Thoroseal that it requires a concrete surface and cannot be applied to pool plaster. <Correct> I am looking for a dark color sealant that I can apply to the current pool plaster, do you have any recommendations? And how long would these sealant last? I am in San Diego and wonder if there is such a product available. Thank you, Theresa <Mmm... I do have suggestions... but expensive... W/o seeing the state of the current plaster, the work behind it (no re-bar shows through I hope/trust) my carte blanche advice is to have the pool re-plastered... in a color of your choice... but will cost some thousands of dollars... On the extreme other end of the spectrum, I would leave all as it presently is... the algae/overgrowing the present poor plaster will not matter in appearance... In-between, you might look into Thoro's other consumer products like Water Plug... or similar from the fine Dry Lok product line... for partial or total re-coating... Do mix only small batches. DO get some help if doing this yourself... as it is very tiring to apply. And, of course, do feel free to write back if you have concerns, further questions. Bob Fenner>

Sealing toxic effects of hydraulic cement 10/19/07 Robert, <Dana> I read with zest (and hope) your articles, FAQs, and related links regarding leaky ponds, but I could not find a solution to solve my dilemma. You're probably going to laugh hysterically when you read about my problem but here goes... We have a very old and small (<500-gal.) above-ground fish pond. Three large goldfish and one river perch have called it home for years. It's base construction is river rock, concrete, and a thin coating of Gunite (leftover from an in-ground swimming pool installation). We used to run a 3/4 hp pump for circulation but over the last few years the pond lost so much water daily that we no longer had to aerate the water. <... for 500 gallons? I'd very seriously look into more/modern pumping here... Will save you a bundle in electrical cost> We let a garden hose trickle into the pond to replenish the water. [Are you smiling yet?] Anyway, we were recently given a large supply of left-over building materials, including about 80 lbs of Quikrete Hydraulic Cement. Sooo, you guessed it, we lined the entire pond with hydraulic cement. Yes, you read correctly, the entire pond was meticulously hand-lined with concrete plugging material. [Are you laughing aloud?] It should be waterproof, yes? <Hopefully... if the basin itself is not "moving", badly cracked...> My dilemma is this... we want to neutralize any toxic effects of the hydraulic cement by applying a safe non-toxic top coat or paint. Therefore, please recommend a suitable Thoro product. Do you think their waterproofing paint would be safe for the fish and sufficiently block any toxic effects from the hydraulic cement? Please advise. <Mmm, their Thoroseal should do it... You can color this if you want... with an oxide/coloring agent... available most everywhere. Though will be about what it's going to be in time with algal growth> Many thanks for your invaluable information. Dana <Welcome. Bob Fenner>

Thoroseal - Potable Water Tank Application 9/20/07 Dear Sirs: In true appreciation of your dedicated help site, I am trying to submit my question as crisp & short as possible. I hired a local professional contractor to waterproof underground potable water tank (concrete cast-in-situ). The contractor proposed using Thoro products - Waterplug for corners & Thoroseal coating for all walls with a 72 hrs water hold test after completion and application as per product data sheets. The present stage is that his application is complete and is asking to start the water test and pay his final installment. I asked for the saline wash / scrub mentioned in Thoroseal datasheet for potable tanks / swimming pools / fish tanks. The contractor stated that he has not done this for the last 20 years in business and that Thoro seal is non-toxic and does not require a saline wash. Please enlighten me because I do not want to insist and hold his payment for something too theoretical but also would not like to get the children living in the house to acquire irritants / diseases. Thanks & Regards - Anwar <Hello Anwar! I'm not sure I can answer this question with any degree of certainty. I'm not familiar with the product or the technique. But my recommendation would be this: if the manufacturer says you need a saline wash before the pond is safe for fish, then have the contractor do the saline wash! If you don't, and then have problems, you will regret it forever. Doing the saline wash presumably won't add much time or cost to the thing. It may even be something you can do yourself. Sincerely, Neale>

Re: Thoroseal - Potable Water Tank Application 7/22/07 Respected Neale: Many thanks for your reply, but you are saying that you are not familiar with the product whereas your Mr. Bob Fenner recommends and describes many Thoroseal applications. Please can we have a specific answer as i believe that the work should be done by the party responsible and not just that it is low cost / less time so i should do it myself. High Regards & Waiting - Anwar. <As I said before, if the manufacturer says you should do the saline wash before using the pond for fish, then do the saline wash. It seems to me a non-question. I have no idea why your supplier says the saline wash is not necessary. It is like having a can of beans that says "Cook thoroughly before eating" on the can, and then asking someone "Should I cook these beans"? I can't speak for Bob Fenner's opinions since I'm not Bob Fenner! He'll read this message before posting it, and if he has comments to the contrary of mine, I'm sure he'll add them. Cheers, Neale.> <<Heee! I have seen this material used in potable situations... I would lightly acid wash the surface for it to be applied to and apply per directions on the bags. Cheers, Bob Fenner>>

Re: Clear waterproofing for ponds, repairs 11/10/06 Hi Bob, In regards to clear water proofing sealer for ponds, we manufacture exactly that - Pond Shield Clear. It can be used right on top on non-glazed tile to water proof it. As I discussed with you before, it's completely non-toxic and fish safe. For people with glazed tile, it can be applied behind the tile, sanded with 60-grit to give it tooth, and the tile can then be set with Ultraset tile mortar. We have thousands of clients using Pond Shield epoxy and they all have great success. <Ahh! Will post your note next to the queriors...> You may still not be a believer in epoxy coatings, but they do work and every time you answer one of your web site visitors and tell them you do not know of a product that works, you are restricting their knowledge and ability to research the market further. <As you might pre/as-sume, this is in reality all I can do, having no direct or near direct successful experience here> I do not expect you personally to give us some sort of endorsement, but when someone like the visitor whose text is below, specifically asks you, you could at least tell them Pond Shield exists and let them make up their own mind. To do otherwise is a disservice to the public. <... please> B. <Not to belittle your products, efforts, or be misunderstood here, I'm so feeble of mind/memory re such things that it simply did not occur to me... the vast majority of our input/output here is aquarium-related... not ponds/water features... My "help" is limited to years back work on these projects> Clear waterproofing... for submersed tile in pond... - 04/26/06 Hi crew, As always... great website and help. Straight to the point, I have a client with a strange request: Indoor pond with white tile to be kept 99.99 % free of algae (lots of brushing). The major problem is with algae growing in the grout. I have thought of using a clear waterproofing product to provide a smooth surface. Any suggestions will be greatly appreciated. Samuel Toscano <<Oh! To just ask you for your URL, link/address to send folks to your site for further input. Bob Fenner> //<I do hope there is something... I would contact tile manufacturer rep.s here first... then the products rep.s they in turn suggest... There used to be nothing that would work well or for long for this application. Two very important notes however... To use the best frost-free tile available for the install period (we used to install Latco/Europa as our first choice here). Secondly to be careful in the EXTREME to not scratch the tile and/or whatever coating you end up applying... as this will greatly expedite algal and mineral accumulation... Bob Fenner, who sees trouble>//

Asphalt Emulsions as Pond Coatings - 10/22/2006 Sorry to bother you with my troubles, but I am a first-time pond builder and am learning by trial-and-error. I recently built an above-ground Koi pond by first purchasing a pre-cast EPDM pond liner from Home Depot. Liner is approx. 5 x 9 x 3 ft. kidney shaped. I then built a stone retaining wall in the shape of the liner, dropped it in and filled the gap with sand. The liner and the wall were roughly level, so I then laid a thick layer of mortar and placed a cap stone ring around the top so the caps all extended a few inches over the pond ( to give a more natural look). I was hoping to fill the pond all the way to the cap stone, but after filling it, I found that the mortar leaked profusely and I could only fill the pond to the top of the liner, also the mortar cured almost white and looked terrible atop the black plastic liner. Then, (after a raccoon family attacked and ate all the Koi one night) I had the opportunity to drain the pond and fix the issue. After a very short and not very thorough research, I decided on roofing cement (tar, essentially) to seal the 3 inch layer of mortar and the crack that had formed between the liner and the mortar. I allowed it to cure overnight, <Mmm, not long enough... takes at least a day for the varieties (some lines of Henry's, Marvin's...> and then filled it and put in another 7 Koi I bought. The tar worked perfectly for what I had wanted, to water seal the gap and mortar, and provide a nice-looking black finish that blended perfectly with the liner. The next day, the Koi were all floating, though amazingly not dead, and the surface of the water was coated with an oil slick, all the pond plants have a black oily residue on them and the white marble pebbles on the bottom are black. <Yes... the emulsion/tar> In retrospect, I see how universally stupid my actions were, but now I need to fix the issue as quickly and cheaply as possible. I don't want to rebuild the pond unless there is absolutely no choice, so removing the tar is pretty much out of the question. <Mmm, actually... I'd drain the pond. let air dry for a week or two... this may do it> I looked into possible solutions for coating over it with something that would seal in the tar from seeping into the water and still have nice slick black look. <There is nothing as far as I'm aware> The other concern is finding something that will also stick to the tar and the EPDM liner. I was wondering what you thought of marine epoxy paint. I read that it has been used over roofing tar successfully (apparently roofing tar is used sometimes to seal boat leaks), and it does claim to be non-toxic. Do you think this is a good idea? If so, what brand would you recommend? <I do not think this will work... no material will permanently bond, long-term to the emulsion> If not, is there a product you would recommend? I am willing to pay the outrageous $120 per gallon (I think I only need 1) if it works, but I can't afford much more trial and error. My main concern is making the pond non-toxic and safe for the fish. Thanks for your trouble, -Sean Edmondson Boise, ID. <I would try air drying the present coating myself... if this is unsatisfactory, another cementaceous material/coating may need to be applied and this in turn sealed/painted. Bob Fenner>

Thoroseal Use in Koi Pond 9/30/06 Dear Mr. Fenner: Thanks for having this info on the Web. Just a clarification: Is Thoroseal (and other Thoro products) safe for Koi? <Yes, once cured> What are the "curing" procedures? <For most of their line, including Thoroseal, simply washing down, draining such rinse water... after the requisite (usually a day) period of time has passed... to "set up"> It's just not clear in any of the text I've read. Thanks in advance for any info you can give. Sincerely, Rose Marie Reynolds <Clarity is pleasurable. Thank you for asking/writing. Bob Fenner>

A cmu reflection pond... sealant? 9/21/06 How do I waterproof a cmu <? Carnegie Mellon University?> pond with a concrete foundation. ½' plaster finish? <Mmm, no> What product should I use? <Is this to be a biological system or poisoned in some fashion? Is there a concern with the present material somehow mal-affecting the water?> Is there suppose to be a waterproof membrane below the plaster finish? <I would not install one at this time... this should be installed first if used...> Any help would be greatly appreciated. Thank you very much. James <There are a few brands, classes of materials that can be bonded to new/ish cementaceous materials to render them waterproof, chemically inert... Please read here: http://www.wetwebmedia.com/PondSubWebIndex/thoroselart.htm and the linked files above. Bob Fenner>

Clear waterproofing... for submersed tile in pond... - 04/26/06 Hi crew, As always... great website and help. Straight to the point, I have a client with a strange request: Indoor pond with white tile to be kept 99.99 % free of algae (lots of brushing). The major problem is with algae growing in the grout. I have thought of using a clear waterproofing product to provide a smooth surface. Any suggestions will be greatly appreciated. Samuel Toscano <I do hope there is something... I would contact tile manufacturer rep.s here first... then the products rep.s they in turn suggest... There used to be nothing that would work well or for long for this application. Two very important notes however... To use the best frost-free tile available for the install period (we used to install Latco/Europa as our first choice here). Secondly to be careful in the EXTREME to not scratch the tile and/or whatever coating you end up applying... as this will greatly expedite algal and mineral accumulation... Bob Fenner, who sees trouble>

ACRYL 60 & THOROSEAL 4/4/06 Where can I get these in Orlando, FL? <Independent "sand and gravel", stucco et al. outlets. Look in your local "Yellow Pages" and call them re. Bob Fenner> Resealing a concrete pond 2/17/06 Hello Robert, <Helen> I have found your site very helpful and interesting. I am repairing a pond that has been sealed with swimming pool paint that still leaches lime. <... then it is not sealed> The pH was unreadable (it was so high). The paint had several bubbles and was peeling. <Very typical... I don't know that the conditions exist for such paints real application> I proceeded to drain the pond and scrape as much as of the paint off . I plan to power wash and give it an acid wash before I reseal the pond. Now I am wondering if Thoroseal will be the product to use if I can get it here in Barbados or if I can use a product called asphaltine recommended by the manufacturer here. <Mmm... likely a "tar-based" material (commonly labeled as roofing materials here in the U.S.)... not really good technology... and a mess to try and remove> I am also looking at another clear sealant. <These are feeble... don't have enough "body"... almost never work> If not I may have to import the Thoroseal from Miami if push comes to shove. Any advice?? Many thanks, Helen Knighton St. Lucy Barbados <Either Thoro's product or something equivalent. Ask about at a local "stucco", cementaceous product supplier... They will know what can be used. I would go with something like Thoroseal here. Bob Fenner>

Re: Pond sealing 2/23/06 Hello Robert, <Helen> I finally found a product here in Barbados SBR bond which I mixed with white Portland cement to seal a concrete pond. I discussed this with the chemist at the manufacturing plant. I asked him about Thoroseal and he knew about it. <Yes... such products are "mixed", not made and shipped about long distances...> He says that with SBR bond and white cement made into a slurry and applied to the damp concrete (keeping it damp is tough in a hot climate like ours) will work. Well I have applied several coats of it and am wondering if it will really work and if is toxic to fish. The chemist claims not, due to the low toxicity and once it has cured. Can I give it a saline or vinegar wash to remove any residue before filling the pond after a week of curing? <Yes, a very good idea> Many many thanks, Helen Knighton <Do test the resulting pH, alkalinity once you're filling the newly coated and washed pond as well. Bob Fenner>

pH of mix water and Thoroseal 11/11/05 Another websites dealing with Thoroseal indicate that it is not to be used to contain water that has a Ph of less than 7.2. What has been your experience with this recommendation? <Mmm, don't even recall... if I/we ever met up with this... the water out here in the Southwest U.S. is pretty uniformly hard and alkaline...> This information is shown on the Rubberoid website which is distributor in Great Britain. I called Thoroseal in the States, they confirmed this information. <... then I would likely bolster the pH of mix water... Easy to do with simple sodium bicarbonate (baking soda)... Cheers. Bob Fenner>

Question.. Statement? Purchase Question 11/2/05 Where can THORO SYSTEM PRODUCTS be purchased in Gloucestershire. Thank You. <I'd contact the company directly re: http://www.thoroproducts.com/ Bob Fenner>

Finishing a watertight concrete pond 10/19/05 Hi Bob, <Chris> First I have to say that your site has been an invaluable resource in helping a beginner like me feel that they have a handle on a project as complicated as a pond. :) I never would have guessed that they are such complex things! <Ah, good> I have read as much information as I could on your site, but my situation seems to be a bit unique. I have a concrete pond which used a 4000psi mix with fiber mesh added, poured overtop a mesh and rebar foundation. <Summat like the construction of a swimming pool> The concrete itself is completely watertight. <Mmm, not really> However, the concrete was beginning to set as the contractor was trying to shape up the surface, and as a result we did not have the time to get a nice uniform surface on the concrete. In some areas the surface is very jagged where rocks surfaced, or has crevices and voids between 1/4" and 1/2" deep. <Yes... usually such "pools" are surfaced with a "cement plaster coat"... actually white/Portland/plastic cement, sharp sand and water... perhaps with color...> I have put some pictures for you to see here: http://www.chrispitude.net/index.php?album=house%2Flandscaping%2F10_16_2005&dispsize=1024&start=0 Start at IMG_8798. To see more detail, choose "Original size" in the dropdown box at the bottom of the image. I do not wish to let ice have an opportunity to form in these crevices. I'd like to put something on the concrete surface which will both fill in any voids, as well as provide a uniform slightly rough surface for organic life to grow on. Thoroseal seems overkill for these purposes, since my concrete is already watertight. I saw a "heavy duty masonry coating" from Quikrete at the local big box store. What should I use to get a nice rough sandstone-like finish on my pond? Thanks Bob! <Mmm, if it were me, mine, I'd (quickly, as the longer you wait the less anything will "stick" to the existing work), decide on whatever... and have it applied, apply it. First off... this is really hard work... heavy, caustic (alkaline), and can be very hard on ones back. Being lazy and well-too experienced, I would seek out the professional services of a "pool plastering" company... You'll find them in the Yellow Pages and such under "Swimming Pools, Contractors, Repairs"... They have the mixers, pumpers, folks to knock this out in a day... worth the money if you can afford it... I'd have them add an oxide (dark, of whatever color) to the mix they'll trowel on... Alternatively, you can try another "dressing"... as you list... It all needs to be applied at once... that is, the same day... so do be careful re what quantity you order (Do look into having it delivered)... adjuncts can be added, like color and "glue" to make all stickier, as well as lime for the same purpose (do wear gloves, prevent the dust from all this from getting in your eyes, on your skin... I do use Quikrete's inexpensive post mixes... but am hesitant to suggest their other products... Again, I would at least get a few contractors bids, input... If you do the work or they, the basin needs to be acid washed ahead of application. Cheers, Bob Fenner>

Your Thoroseal article and acid wash 9/1/05 Bob, <Charles> I enjoyed your article on Thoroseal and pond repair at http://www.wetwebmedia.com/PondSubWebIndex/thoroselart.htm. You mention an acid wash before introducing livestock. Does this include Koi? <Yes> I could not find the article on acid wash. Do you have a link? <Here: http://www.wetwebmedia.com/PondSubWebIndex/acidblchpds.htm> I read as many of your pages as I had time and could not find this information. Thanks, Charles <Is on the Pond subweb index, can be found by using the search tool... Bob Fenner>

Water garden coating 8/16/05 When constructing my home, I had an above ground enclosure built on a sloping side, so I could add a water garden. It's approx. 7 ft by 4 ft by 3 ft deep. Two walls are brick and two are foundation concrete blocks. I plan to coat the inside surfaces with Dry-Lock for a water seal, but it is white. I'd like the inside to be black. <Mmm, you can add color/pigments to the Dry-Lock...> Is there a "simple" paint that would be safe for fish and aquatic plants? I've read about neoprene coating and epoxy paints, but they sound like more than I need. The surface will be waterproofed by the Dry-Lock. I just want it to be black. Thanks for your help. Ojay <There are a few routes to go here... the simplest, cheapest are asphalt emulsions... a bit messy to apply, and need to be completely cured before immersion... but beautiful, inexpensive. As you mention, there are rubber, epoxy "pool" paints... these need to be carefully investigated, applied, using the manufacturers thinners, instructions to the letter. Bob Fenner>

Re: water garden coating 8/17/05 Thanks for your quick response. You mention that the Dry-Lock can be pigmented. True, but only slightly, yielding light colors. About the asphalt emulsion, am I looking for a certain type? One I just checked out was for patching asphalt drives, but it said not to use it on concrete. Ojay <Mmm, can't recall the numbers... for Henry's or Marvin's... I think 104 or 107... Need to read the cans, maybe visit these companies websites. Bob Fenner>

Pond Armor, failing product, leaking pond 7/16/05 Hello, <Hi there> We found your site too late. We also had a bad experience trying to seal our pond. Can I still use Thoroseal if I already have something on the concrete. <Depends on what that/this is...> We bought something called pond armor. It is a two part mix in quart cans. <Is it this: http://www.pondarmor.com/> It seems like an epoxy of some sort. I have put several cotes on and the pond still loses water rapidly. The concrete pour done by the contractor was not good. I had to fill a lot of cratering in the walls as well. He disagreed that the pour was... well poor. It was too dry and set up before packing down smoothly. I suspect I'll have to re-construct in a few years, but I need to get by for a while on this build. I cannot afford the time and expense of jack hammering and re-pouring right now. <...> This was a new build with new concrete that is now totally covered by the failing material. Should I try to use another coating of something that will stick to the coating I already used? <From reading this sites spiel... what terrible pix!... am not hopeful that much of anything will "stick" to it... Am back to my usual advice here... to pretend that you just have a hole in the ground... and build a new pond (with a liner et al.) inside it> Thanks for your page. Please help. Talon <Good luck with your project. I wish you well. Bob Fenner>
Re: Pond Armor 7/16/05
Robert, <Talon> Thanks for the quick reply. The link you found is the stuff I used. The biggest problem is that it does not cover as much square footage as reported. We had to re-order another two applications at $75 a pop. <... what a rip... there are times when I wonder whether the premise of "original nature" of humans is off... That is to say, whether this is "good" or "neither" good/bad... To the point, would I be willing to sell people this stuff with the spiel listed? No... too many ponds built, failed coatings seen... even if this material covered the purported sixty square feet... ten mils nominal... for $75... I wouldn't be able to look folks in the eye> The pigment part is a full quart. The activator or catalyst is about half a quart. You end up with less than a quart and a half when you get it mixed. They claim sixty square ft. at 10 mils. That simply does not happen. I estimate I got through about 40 sq. ft. at maybe three mils. A lot gets wasted trying to get it out from under the lip of the can and out of the mixing bucket. <Oh, should have read your input first... Scam!> I thought I would share this info with you in case anyone else asks about it. I think the product would have been fine if we could have gotten enough on the surface. It is just too expensive for the sq. footage. I figure I'll just have to abrade it and goop it up with some kind of less expensive product. <What if the basin "moves?" or folks have rock et al. elements penetrating same?> To their credit, the staff was quite willing to consult and had great follow-up. Now, if they would just send enough to finish the job we would be in luck. T. <Am still not a buyer. BobF>
Re: Pond Armor 7/16/05
Robert, <Talon> I have one last question and I'll quit bugging you. Since the Thoroseal is not an option, do you know anything about a product called Sani-Tred? http://www.sanitred.com/WaterFountain.htm I may try this next unless you know something better. T. <Says is "liquid rubber based"... I would definitely chat with someone there re its adherence to the epoxy before purchasing... try out a small area... Bob Fenner>
Re: Pond Armor 7/22/05
Mr. Fenner, <Butch> My name is Butch Kuhl. I am one of the owners of Pond Armor, producers of Pond Shield. I know from your Daily FAQ over at Wet Web Media that you are at least familiar with our name. <Yes, just recently... from a query, reading your website> Let me start off by saying that there was a bit of a debate between my business partner and myself as to whether or not we should contact you. Frequently, when exception is taken to advice given on a FAQ/Q&A site, the moderator will take it personally and use specific quotes out of context to distort the intent of the message. <Mmm, I try not to misconstrue... nor give "advice" re anything I don't have first-hand experience with... unless this is stated emphatically> In the end, all one can do is hope that the person being contacted is reasonable and is open to listening. We hope that you are this type of person. Recently you answered an email from a person who had some problems trying to seal their pond. After reading the details about this pond, I recognized it as one I dealt with just days before. When customers call in and speak with us about our coatings and how to best proceed with their project we take a lot of notes and record as much detail as possible so that we can guide them through the use of our product for their particular project. <This is wise. Know that I was a contractor, designing, building water features for two decades... did forensic work... re folks suing people... among the complaints, most often for failed sealants> It's in this way that we can try and help them not miss or skip steps in the process of preparing and applying Pond Shield. For now, I'll move on to product details and we'll come back to this project afterwards. <I do re this> I'd like to spend a little time here explaining to you what Pond Shield is and how it came about. As you know, there are a great many coatings for the pond enthusiast on the market today. Each has at least one advantage and in most cases several disadvantages such as; poor color choices, high price per square foot, installation ease of use issues, life span, toxicity, hidden costs, aesthetics, or material composition. <Well-stated> There are many more disadvantages but those I listed are probably on the minds of pond owners more than most. Now if you couple that with the fact that not all ponds are created equal, you end up with huge variety of issues regarding pond projects being built today. Let's face it, pond owners are some of the more creative people in the home and garden world and are willing to go to great lengths to create their dream ponds. The problem is that the majority of typical end users may not be ready to perform many of the so called "do it yourself" tasks required to get that dream pond from conception to completion. This can either stem from a person that skips or skimps on required steps or in some cases to the lack of knowledge to perform a particular step needed to finish a project properly. So the responsibility of a coating manufacturer, like Pond Armor, is to try and keep the coating system as simple as possible to eliminate or minimize as many of the negative factors that can arise during a typical end users pond project. <Agreed...> This in turn means that someone, like a professional pond builder or contractor, who already is knowledgeable about this sort of work, can perform the tasks needed much more easily than consumers not in the trade. What it boils down to is that if a product is designed around a consumer with minimal construction skills in mind, then everyone from that benchmark up should be successful with their project as long as they perform the necessary steps indicated. With the creation of Pond Shield, every negative factor we could conceive of was discussed and dealt with before the coating was released to the general public. For instance, it is possible to spray our epoxy but we made sure that in a worse case scenario, a roller or a brush could be used to apply it. The instructions we give out with the product offer the best and easiest possible explanation for preparing your pond and eventually applying the coating. Customers that call in and ask questions get even more assistance because they can chat with us about their specific projects. In some cases our customers even send pictures of their ponds in so we can assist them. Our epoxy is derived from a more industrial version of an epoxy we have been using for the past 15+ years on projects like trout hatcheries in Canada and water treatment facilities. <Yes> With proper care, our epoxies can last that long and longer. As I mentioned earlier, one of our concerns was toxicity. Instead of dealing with this issue by testing cured samples of our epoxies, we tested uncured samples! We figured the worse case possible would be the customer that didn't mix the epoxy thoroughly and had spots that hadn't fully cured before he/she filled their pond with water and added fish. So the tests were performed and our epoxies were deemed non-toxic, ensuring us that poisoning would not ever be an issue. One of the other great concerns regarding coatings has and will always be price. We have priced our epoxies so that they are very competitive in the current market. We made sure that ease of use keeps our prices low when comparing them to materials and installation of products like Polyurea or CIM. It's common knowledge that Polyurea sprayed pond liners are cost prohibitive and coatings like CIM are indeed very finicky and troublesome for anyone not familiar with their application. In comparison to a product like Herco, Pond Shield does not require thinners or special primers (that amount to a hidden cost) to complete a project. In fact, even though Hecht Rubber Company's web site states you need to thin their material and apply a primer, you won't find those instructions on a can of their neoprene rubber coating. I know you have recommended that people use Thoroseal as an option but like many other coatings of this type it can be troublesome for end users. <Yes... to be clear, specific here... Thoro products have as you state so well, only limited application... not useful for basins with substantial cracking, shifting...> I have spoken to many people that were considering the use of Thoroseal but had no idea how to apply it anyways. I'm pretty sure that if you compare skill sets, applying paint on with a roller is considered easier than floating a plaster type of material. <Mmm, can be applied with a brush...> In fact, I have contractors that tell me how thankful they are that they don't have to waste man hours on Thoroseal anymore and have switched to using Pond Shield. In any event, you get the idea. <I see the point you are trying to make> Now as far as the person mentioned above, I'd like to point out what the problem with that pond actually is. After the home owner contacted us indicating a problem we had them send us photos. It is clear from those photos that the concrete was poured poorly. <Happens... all the time> What happened as a result of that was that many holes in the surface - that ranged in size from minor imperfections to holes big enough to stick your finger into up to the second knuckle - were created. <...!> Unfortunately for the customer, the only way to take care of the problem was with some sort of surface render prior to coating. We were not made aware of the how drastic the surface imperfections were at initial contact. Instead of referring to the surface area as pitted in any way, the customer referred to the concrete as being porous. All concrete is porous <Yes> so we never even realized there was a potential issue. Hence the first coating that was put on the pond failed. After subsequent emails (one containing a picture of the home owner inserting a finger directly into the wall of the pond) it was discussed that the best course of action would be to fill all of the holes and recoat. As our epoxy systems allow other plastic type materials to bond to it, <A very good feature> we decided that plastic fillers with thickening agents be used after the Pond Shield was abraded with at least 60-grit sand paper. Once the filler had cured, a fresh coat of epoxy could be applied to finish seal the pond. As it turns out, the second coating failed (due to the fact that the home owner did not adequately fill the hundreds of pitted and large holes throughout the pond) and you were asked for advice. Your response on your daily FAQ has led me to contact with you. <I appreciate it/this> Advice and opinions can come from varying sources and we understand that. However, advice and opinions offered by persons or organizations should be done with knowledge gained through experience and/or due diligence rather than just casual observation - especially when those asking for information are truly in need of assistance. Frankly, we believe that some of the comments you made in this discussion were not made with the benefit of anything other than casual observation. <Mmm, let me take a look We believe that this lack of due diligence on your part has caused you to give poor advice <I don't give advice... only tell folks what I would do in similar circumstances... My comments are only in direct response to the input provided... Here: http://www.wetwebmedia.com/PondSubWebIndex/thorselfaqs.htm> to your readers and given a completely false impression of our company and its product. In the specific case that began your comments, I do not believe that the person asking for help was given the most responsible advice. Really, telling the person to start over without knowing the specific details of the issues? <... please read my comments, responses again... Given the scant information... it is my abiding opinion that this person should actually "start again"... treat the hole they have as such, use a liner, reinforcing wire... Not try any coating, plug...> I think referring the person back to the coating company would have been a good first start. <As... you'll see was done...> As it turns out with this customer (in asking the home owner for more specific information) I requested more pictures of the pond after the second coating failure. As stated above, there were still more unfilled holes. Holes that had not been fixed, thereby causing the same leak issue it has at present. Now, restating what I stated above, if the pond is prepared properly and the coating is applied properly as we explain in our instructions, failures like this won't happen. <If the basin/s are otherwise stable...> To have so casually blamed our company and disparaged our product (as well as calling us a scam and a rip) was reckless and unfair on your part. Particularly so, given that we created this company with a real desire to make a better product that would be beneficial to pond enthusiasts. <Sir, the cost of your product, the stated coverage... is what my reaction is/was based on... I would not use this technology period> Does this mean failures will be nonexistent? Of course not, I make it clear that while our epoxies are designed to be flexible in nature and resist mimic cracking of things like mortar joint cracking or hairline cracks that can form in concrete, this does not guarantee that cracking cannot occur. Usually, when cracking occurs, it is an indication that something may be happening with the surrounding substrate. In which case, if you have severe movement or a root pushing up through your pond, you have worse issues than a coating failure. Regardless of the coating used, even a bare concrete pond will not withstand that sort of abuse. <In S. California where the ground moves a great deal, we always utilized underlayments (liners). Our companies installed many such features, of several million dollars total cost, over decades of time... We "lived through" the use of asphalt emulsions, chlorinated rubber paints... and epoxies as yours...> Just as you educate and inform your readers I hope that you will give me an opportunity to do the same for you regarding our product. We have many contractors and sophisticated pond hobbyists who praise our product and enthusiastically use it. I invite you to contact me at any time to chat about our products and become more familiar with them and with us. We are people who love ponds. We are also people who love helping our customers achieve their goals. On a final note, in response to your posted answer, we are quite able to look each of our customers in the eye knowing we have made a major improvement to the lining choices available to those people who use our product. My phone number is 1-800-716-1545. We are moving into our new manufacturing facility beginning Friday and will have operations shut down while setting everything up next week, so if you have to leave me a voice mail please be assured that I will return your call as soon as possible. If after talking, you are interested, we can get you a sample to try out and see for yourself that we are offering a quality product like none you have ever used before. It is my hope that after reading this, discussing the issues with me and using a sample, that you would take it upon yourself to post a retraction of your statements on your site. Who knows, perhaps you will find that using Pond Shield truly is the advancement we believe it to be when compared to older linings/coatings. <... you are welcome to contact me through the Net... I have a title coming out soon re Water Feature Design, Construction, Stocking & Maintenance... I will gladly send you a copy. Thank you for proffering your side of this instance, offering your input/side, being forthright re company, it's re-packaged product. I wish you well. Bob Fenner>
Re: Pond Armor 7/25/05
Mr. Fenner, <Bob is fine Butch> I appreciate your reply and the time you took to take a look at our letter. Please excuse me for replying so many days after your response but as discussed earlier, we are in the process of moving. I would like to clarify a couple of points if I may. <Please do> First, Pond Shield is not a repackaged product. It is derived from an epoxy we already had. That is to say we took one of our existing more industrialized epoxies and modified it for hobbyist use and pond application in specific. It is a new product. In fact, we believe that using this new product in it's non-pigmented form (Clear Pond Shield) for one, will allow hobbyists and contractors alike to build PH stable ponds never dreamed of before with materials such as exotic woods, metals, tile, and stone. This is a new product for people with a new vision of ponds. <... after being in the trade for many years, I am doubtful as to all other technologies than liners> As for the stated coverage, if you do the math, you'll find that our epoxy works out to only about $1.24 per square foot for consumers (less for contractors). That's far less than other epoxies, plastics or rubber sealers on the market today - especially if you take into account hidden costs for primers or thinners that are required for competing products. This, amongst other things is why our epoxies are unlike any other epoxies on the market today, so it's unlikely you've used something like Pond Shield before.
<... liners are about a quarter of this cost... last forever>
Finally, I believe that the information given to you by the poster led you to make inaccurate statements in response that have put out company and its product in an inaccurately unfavorable light. Given the circumstances, I hope that you feel, as we do, that it would be appropriate of you to remove any references form this post and it's thread from your site archives. <No...> In any event, I still welcome you to contact us and use a sample so you can better evaluate what we have to offer. Thank you, Butch <Mmm, thank you again, but no... I am long-since retired from actual practice in the field. I do believe you, your company have some future, application... but given my knowledge of the past... for all coverings... of all make-up, and the public's use thereof... I would not continue... it's a litigious world here in the west Butch... though your product may work fine as stated... Bob Fenner>

Thoroseal Use Wed, 16 Mar 2005 Good Afternoon Mr. Fenner Robert: <Buenos dias Carlos> I am thinking of using the Thoroseal Waterproofing cement on my concrete pool deck. <Bueno> May I ask if you recommend this and what concrete dye did you use? <These are made for the stucco and concrete business... Come in powder form... one and five and larger pound size containers> Where did you purchase this? <At/through local concrete et al. companies. Mainly Expo Stucco here in San Diego> I live in Southern New Jersey. <I would look in your "Yellow Page" directories under "concrete", make a few calls... You'll soon have what colors, accents you're looking for. Bob Fenner> Thank you for any assistance and advice you may offer. Best Regards, Carlos M. Ingravera
Re: Thoroseal Use
Robert: <Carlos> May I ask 2 more questions. Hope this is not bother. <Never a bother> 1-Do you think it is wise to apply the Thoroseal on a pool deck, making it impervious to water? The concrete won't "breathe"? <Good question... actually, if the concrete is "more" cured... a few weeks to months old... this is not really a concern. What IS important is to make sure the surface is absolutely clean... likely to "acid wash" it... and if there is any biological material (e.g. algae) to bleach wash it before, make sure it's dry and then acid-wash/etch it ahead of time> 2-Should I apply a sealer after coloring? <Mmmm, I would ask the folks selling the Thoro product... am thinking there may have been improvements in this technology since I used it (last some fifteen years back). There may well be good sealers nowadays... Back when they weren't worth a hoot> I am originally from New York, but I love Jersey, though I was conceived in Los Angels.... Carlos <Ahh, and I was born in Rhode Island, but have lived outside the U.S. more than half my life... currently reside about half the year in San Diego, California. Bob Fenner>

Appropriate paint I'm repairing a crack in a concrete fish pond that came with our house. I chipped out and filled the crack with Thoro Waterplug, and now I looking for a paint/coating I can use to match what is already there. The pond is dark green, but the only suitable paints I can find seem to be so light (white, blue, gray, beige) they cannot even be tinted to match. Can you suggest something? Thank you, Bill Crowell <I hope so... depending on the rest of the basin coating... hopefully it can be acid-etched... after being bleach-cleaned... see WetWebMedia.com re... can be coated with another cementaceous material, like Thoroseal... that has been colored with pigment/oxide... take a sample of the color you're looking for into where you bought the WaterPlug... and they should be able to match it... If this is, or you want (I would NOT in a biological system) to coat this basin with an epoxy or chlorinated (pool) paint... Nelson, et al. do make such. These should be able to be procured through a large swimming pool supply. Bob Fenner>
Re: Appropriate paint
Thank you very much for a most helpful answer. Bill Crowell <You're certainly welcome. Do take care if/when applying the CR or epoxy paint's... and follow the directions for application, preparation "to a T"... these are "finicky" products... Bob Fenner>

Thoroseal for rock pools Would you recommend Thoroseal for the pool Gunite sealer as well as different colors for the actual concrete structures? Thanks Respectfully Submitted, Glenn Vodhanel <Mmm, actually... IF you've paid for Gunite installation (almost always Union), I would go ahead with having the same contractor arrange for "pool plastering" for color and seal... though, yes, Thoroseal or similar could be employed. Bob Fenner>

Pond Sealing Hello: I found your write-up regarding foundation coatings for water features. We have a 10-15 year old pond in Carlsbad (part of San Diego where RMF lives as well). I plan to take your advice and use Thoroseal to refinish it. The pond has a waterfall and is decorative only. We do not have fish. Do you have a suggestion for color for the finish? <Something dark... as it will become so (and quickly this time of year) with algal growth> I'd like to minimize the impact of dirt that creeps into the pool, so something dark would be good. Does Thoroseal come in colors other than gray? What kind and how much color pigment should I add? Thanks, Curt Yaws <Can be easily colorized with oxide agents... do call on Expo Stucco (in Miramar area still I think) re their selections... and they are a big distributor of Thoro products. Bob Fenner>
Re: Pond Sealing
Bob: Are you available as a consultant. I like to do projects myself, but prefer to get good advise before I mess something up. I have just water blasted my pond to clean off the old Thoroseal and have several cracks. Also, the concrete is quite rough now. I'd be happy to pay for a short visit. Curt Yaws <Do occasionally get out and about... reminds me, I've got to call the folks out at Lakeside re a water feature they're putting in... but am out of town till the end of the month and then back out soon for another week. Are the cracks "expansive"? If they're small (less than an eighth of an inch across) and old (years) you might be able to effect a repair with a non-elastic fix (e.g. cementaceous materials)... if not, the liner repair route is suggested. Bob Fenner>

I found your article on Thoroseal... We have been looking everywhere for a how - to and which products to use to resurface our 3 year old cement pool slide. Do you have any recommendations? Would this work? Is it sleek after it's dry? Thanks so much, Cheryl Foster <This is a very good product (line) for biological pond repairs, sealing... Not really smooth though, and that's what you want for a slide. I would enlist the help of a pool plastering co. here... and roughen, and re-surface the slide with a cement "plaster" coat... of good plastic cement, sharp sand... and good white "glue". Get some help if you've never done this before. Bob Fenner>

Acid Wash (for ponds) >From your article on Thoroseal..... 10) The coating should be lightly acid-washed per the Section of the same title, to reduce alkalinity, before introducing livestock I can't find a section on acid wash.
<Tis here: http://www.wetwebmedia.com/PondSubWebIndex/acidblchpds.htm >
I have completed my Thoroseal Foundation Coatings and now need to know the acid wash procedures.
<This is the protocol we used. Please contact me if you have questions, concerns. Bob Fenner> Thanks........ Carl Hopkins

Thoroseal Hi, I just stumbled upon your website which includes a "how-to" for the use of Thoroseal. We appreciate you promoting Thoro products (which along with Hydrozo and ThoRoc became part of ChemRex in 1999), but giving out correct information as to their use would be even more beneficial. <Mmm, hopefully I can find what you're referring to as "correct information". Would you state categorically what you mean?> Below are technical data guides for Thoroseal and Acryl 60 (not Acrylmix 60). If you would like to visit our website, you could obtain current tech data guides for other products as well. If you have questions concerning the use of our products, please contact our Technical Service Department and we would be glad to help you. <Thank you for this input. Will make corrections, and post your note. Bob Fenner> (See attached file: 87916 Thoroseal TH145.pdf)(See attached file: 87913 Acryl 60 TH101.pdf) Joan Kaufenberg ChemRex Technical Services www.chemrex.com
Re: Thoroseal
Since receiving your memo, I had our IT Department scan the network for viruses and it was clean. I also scanned my own PC and it also is clean. You could have a problem at your end. <To be clear/er here. On attempting to open your .pdf file, the MS software that is Hotmail stated there was an unidentified virus there...> You can easily get the tech data guides I sent you by going to the website I previously gave you. Joan <Very well... Will likely just post your comments, link. Bob Fenner>

Questions about Thoroseal I would like to use Thoroseal on my pond cracks that run alongside the top perimeter (after I patch them with WaterPlug). <Good idea...> I had planned on draining the water in the pond to the level where I can work on the pond, but I cannot empty and remove the fish for the process. <Hmm... I would get/use a kiddie wading pool, shade, cover/net, aeration, filtration... and remove the livestock...> My concern is that I won't be able to acid wash the pond because of the fish. Do you have any suggestions of a non toxic rinse or a wash that would not affect the fish? <There is none as far as I'm concerned, aware... best to settle on the fact that you will be removing all from the pond to do the job properly... Bob Fenner, who has "been there, tried, done, re-done that many times"> Thanks! Maria, Baltimore, MD

Thoro products Hello, I am in Atlanta, GA, USA, searching the internet for references to a product I have used successfully in the past, and with no competition - Super Thoroseal concrete waterproofing material (powder form, mixed with water, then applied to concrete surfaces in need of waterproofing). I am having difficulty finding a U.S. distributor or retail outlet for that product, and am currently in need of it for a construction project. If you can provide any information, my appreciation in advance. If not, please pardon me for your time. Best regards, John Vassar <Hmm, was able to trace down the company that now owns Thoro, and their site to get you where you want to go: http://www.afsonl.com/homes/1651/ Bob Fenner, who really likes these products, and has used tons of them.>

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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