Pond... plumbing, shape design...  10/3/07
Hi folks, I respect your request for avoiding questions that the user could find in the FAQ or with Google. I found your site with a Google search and I don't see my question answered anywhere yet so hopefully, I am not creating undue burdens here, and thanks very much for setting up the space to ask.
<Welcome>
I am now facing taking over someone elses project at mid point.
The contractor apparently had a shady side and is now in jail.
<Yikes!>
Looks like promises were made and not kept about what was ordered, etc. I was looking at the hole he left last night and I am researching all I remember from my own pond building and pond maintenance days and my landscape design classes to see what I would need to pull this off.
I used to work for a relatively high end pond and water building firm in the DC area. I dug holes, moved rocks, ran equipment and most especially did lots of maintenance on filters and ponds. I never felt responsible for designing the whole thing, engineering the plumbing although I have certainly fixed broken pipes, valves and pumps. And I have some awareness of waterfalls, stream beds, construction and (gulp) leaks. I have also installed some small features for friend's and I usually build my own filters to sit in the pond. This project will be one, or two steps beyond what I have already done. And, I haven't been in the business for over ten years so I am internet researching to job my memory of what we used to do.
<Okay>
The size of the pond is roughly 15 x 30 feet. On the deep end it looks to be over 6 or 7 feet.
<Good-sized... what do the folks in charge "want it to do?">
The pond is roughly kidney shaped and it is already dug out. The contractor left a layer of plastic sheeting over it like a liner, I don't know why. The homeowner said the contractor said he did it to dry out the ground (?)
<?>
Is this a technique that sounds familiar to anyone?
<No>
First step would be to remove it as I am going with my experience installing the underlayment and the EPDM liner.
<Good>
The first thing I notice is there is no work started yet on the plumbing, no skimmer, no trenches or pipes, no bottom drain. So my first question is, common sense from a maintenance background is to install the bottom drain. There is no hole or trench dug for a bottom drain so I have to take care of that too. But I need to research how that works. I have seen it working but I can't remember "how" it runs. I am a little confused with all the different installations I was a part of and I hope I am not mixing one idea with another? I have seen skimmer boxes with the pump inside them.
<Mmm, really?>
In that case water is sucked into the skimmer and pushed through the pipe up to the bio filter which doubles as a waterfall top edge.
<Have seen these...>
In other systems the filter or filters are vortex, bead or other external variety, usually with high nitrate producing Koi, are outside the system and isolated a bit to take the pump sounds away from the pond design. I think this would be over kill on this design for what the customer wants.
<Good units... pricey to acquire and operate, but work>
I also know there is value in adding a waterfall pump and having a regular circulation pump. This allows energy savings when you want to keep your system filtered and healthy but not pay the electric bill or possibly generate noise all the time with the full force of the waterfall. It also allows for maintenance and adjustment to the waterfall without hurting the pond system.
<Well-stated>
That's what I know. What I don't know is about how to set up a bottom drain and valve it to the flow of the skimmer?
<Mmm, can be done through the membrane (with flanges) or inside... via trenching in both... the main drain plumbed to the skimmer directly if one wants... with the second/behind hole going up/out of the system to the pump intake... but I encourage you to have at least two intakes... if you want a skimmer (or two), plumb these AND the main drain separately out, up to the pump...>
If I take on this design, I am thinking that the pump needs to pull water from both the bottom drain line and also the skimmer.
<Yes, this is best>
If true than the design with a push pump in the skimmer would not work.
<Correct... and I am NOT a fan of submersible pumps...>
Is this true? Therefore if I used a bottom drain I would look at designs with the pump in the biofalls or free standing outside or behind the waterfalls. I would need one of these designs to achieve puling the water up the button drain and the skimmer, yes?
<Yes>
And if I am on the right track there, then I will need a valve to adjust the rate of intake between the skimmer and the bottom drain, Yes?
<Correct>
If I read correctly, there is a reason to completely shut off the skimmer if necessary to feed the fish or for skimmer maintenance and if I designed it correctly I could just valve to the bottom drain 100% with no worries. Yes?
<Yes>
Can someone please refresh my memory as to what is the usual percentage of flow between bottom drain and slimmer to the system?
<Mmm, less to the skimmer/s... ten-twenty percent or so; the remaining from the main>
Assuming that in large part this is something you observe once it is running but there should also be a rule of thumb here.
<Yes>
If I read on line articles right and compare that to the ponds I have installed in the past, I believe you don't want the water fall or pond return flow too near the bottom drain, for achieving good circulation mainly. But that is how the contractor has set it up so is this something I should really consider doing differently or is it really going to be a problem?
<Not likely a problem>
I should mention that although I see the wisdom of a bottom drain, if it turns out to be out of the homeowners budget or not completely necessary, I want to consider the design without this feature. I assume this takes me to the simplest solution mentioned earlier of putting a pump in a skimmer box and running a single line to a biofalls. Yes?
<... not if it were my design, no. Much to be related here... the best engineering involves a "passive" system of plumbing that conducts water NOT from the bottom, but maybe 3 or 4/5s the way down... this water recirculated... and a bottom "drain" in addition to simply dump the "bad water" from the bottom itself...>
The other question I have, also important, is about pond construction. This is Denver. I am writing this in early October so I may have a month left before the ground gets too solid. Or, I could have two months let, you never know around here. I am sure there must me what we called frost heave back in Virginia, here in Denver. YOU have to build with a mind to the changes in the soil when it freezes and thaws again.
<Yes>
With that in mind I want to ask about the technique that I remember using and ask for some feedback to see if what I am thinking of doing, makes sense to an expert?
<Sloping sides, good landscape drainage, perhaps a sand bed arrangement around the basin, not leaving the system empty during freezing weather>
I am used to digging more or less vertical walls in the dirt and taking the top 18" down for setting one or two cinder blocks, depending on the strength of the surrounding soil. We laid the cinder blocks on the side and filled the holes with tightly packed dirt. Then we rammed pieces of rebar into each hole. We built some very nice high end designs this way and while it stabilized the bank, or seemed to in the Virginia clay, it also was a way to provide a stable base for large heavy rocks that could be put next to or on, an edge.
<Sounds very good>
I see lots of "how to's" on the web about building cinder block walls form the bottom of the pond, but none using the techniques I am remembering.
<I am unfamiliar with this as well>
The contractor left long sloping edges that I don't like very much. They slope nearly 45 degrees around the shallow end.
<Mmm, yes... not good for maintenance, but better to avoid having the basin crushed, pop-out during coldest weather>
It seems more natural to my mind to cut the edges more to a vertical angle, possibly leaving ledges (yes knowing about predators and ledges). Is there any reason a design would have such largely sloping edges that I am not aware of? It also seems more potentially stable to make a proper wall at the start. And that means pretty much vertical with soft rounding on the bottom edges, more art than science but then, I have been there and done that before.
<As stated>
Thanks much folks. I know I am asking a lot but I hope my questions have provided enough clarity for answers. I would recap this into wall constructions with cinder blocks on the top layer only and bottom drains and system choices for pond mechanics.
If you post my question and your response please omit my phone number and email. Thanks.
David Groover
<Am unfortunately going to be out of Net reach for a couple of weeks soon... Bob Fenner>

Pond Overwintering, not reading   8/19/06
Ok well I live in  Pennsylvania where it is pretty cold and the pond will freeze. How deep does it  have to be.
<Mmm... depends on what you intend to keep in it, where it's located relative to "structure", whether you intend to employ countervailing strategies to prevent it freezing over/all the way to the bottom... 4 to 6 feet likely...>
Also is there any specific brand of food I should feed them or what  should I feed them to get their fat up for the winter.
<Please read here: http://www.wetwebmedia.com/PondSubWebIndex/pdmaintwint.htm
and the linked files above... Bob Fenner>

Pondfishes in the GWN  3/3/06
Hello
I am thinking of setting up a small outdoor pond - 180 gallons - which contains no heater and a basic filter.
<... likely too unstable at this volume...>
I am located in Nanaimo, British Columbia, Canada.
I have a couple of questions:
What type of fish would you suggest?
Can they survive the winter?
<Perhaps some of the local life...>
What happens if the water freezes in the pond?
<If all the way down, fishicles... See WWM re ponds please: http://wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm
See all those blue file names? They're links... Bob Fenner>
Thank you
Pat

Pond article Corr.  1/20/06
Your article was most informative.  However, please change the spelling of the word "irregardless,"  found in the first sentence of the section
entitled, "Shape and Size."  There is no such word, it should be regardless.
<Thank you for this. BobF> <<And looking on Google... there's a few pages of others...>>

Pond depth, poor English 10/13/05
I am digging a small backyard pool (wildlife area) about 15 feet long &4 to5 feet wide .I want to put a few medium sized fish in it .I started digging it two feet deep .is this deep enough or would 18" be enough? Don
<There are economic, practical and legal inputs here... Please read: http://wetwebmedia.com/PondSubWebIndex/pddessize.htm and the linked files above re. Bob Fenner>

Tropical Ponds
Bob,
I see that you answer all the questions regarding ponds on the WWM.com
website, I apologies for the length of this email, but figured better to
send all the details.
<Good>
I have read through the pond section at WWM.com and found it to be very
informative, however I have been unable to find anything on tropical
ponds. I live in Thailand and the availability of pumps, accessories etc
for pond construction is very limited and for that reason most of the
construction will be DIY. I have a number of questions that I have been
unable to find the answers to that I hope you can help me with.
Background details, (The Plan!).
Construction; liner with reinforced concrete and then Thoroseal, (or
equivalent if I can find it).
Pond shape; roughly pear, 5mt long x 3mt > 1.5mt, 1mt high waterfall at
the 3mt width end.
Plumbing ; 4 x 2" outlets, (with debris traps), set in the bottom of the
pond going into a pre-filter using round stones or rough plastic balls.
The inlet to the pre-filter would be at the same level as the 4 outlets.
From this the pump suction would be approximately 3" below the water
level of the pond. Pump discharge is 10.5 Lt per minute, which will go
into a filter. The filter will be 3 stage type using; settling, plastic
hair curler type tubes and then into to the bio-filter chamber and then
into the top pool of the waterfall. I will also include drains/by-passes
and back-wash piping for cleaning in the final design.
<Does sound like you've been investigating. Sounds good thus far>
The Questions
* Most articles recommend a water depth of 3ft, I found 1 forum
article regarding warm water ponds which said this type should only be
18" deep. What would be the recommendation for a pond here in Thailand,
average temperature 28'C, 83'F?
<I would make the pond deeper... more stable all the way around, should you find that you want to keep fishes that appreciate smaller shifts in temperature, dissolved oxygen, pH... Easier to maintain if deeper as well>
* The pond will not be shaded, should I use a UV filter?
<If suspended algal over-growth is an issue, yes>
* Can you recommend any books, web sites etc on the subject of
tropical ponds, with sections on the type of plants and fish species
that can be mixed etc.
<There are many... some in English by Tropical Fish Hobbyist Publications, some in Japanese. None are definitive IMO... I encourage you to try getting, reading what you can from a larger library, but as importantly to seek out others (maybe a pond society there) who have built similar systems in your locale, the input of concrete contractors, landscapers... and the input you can garner from the Internet (on various bulletin boards, chatforums) re ponds. You have a good grasp of what this project is about and will do fine investigating, keeping good notes, sorting out your options.>
Many thanks in advance for any advice you can offer.
Regards
Neil Sandilands
<Bob Fenner>

RE: Tropical Ponds
Bob,
Many Thanks for your prompt reply, I apologize that mine was somewhat
slower, but my work location sometimes has problems with internet
connections. 
<I understand... completely>
I will definitely go deeper as recommended and try and find
some books/contacts in my area, I'll see what happens regarding UV. I
anticipate around 6 months for construction, (due to work schedule),
hopefully all will run smoothly. Thanks again.
Regards
Neil
<Ah, a grand adventure. I was/am involved in a couple of "authentic" Japanese ponds that started construction before my joining and are still "being built" more than three decades later... these "things" take time... Enjoy the process my friend. Bob Fenner>