Reconstruction of Pond: Bottom drain or no?

Discussion in 'Water Features' started by Bbentler, Apr 9, 2010.

  1. Bbentler

    Bbentler LawnSite Member
    from IA
    Messages: 1

    Okay, so four years ago I installed a pond. Now I had to rip the liner out as it became brittle and fell apart and cracks occured. So I am replacing it with a better quality EPDM liner. Now here is the issue: I've never installed a bottom drain and our local pond expert says, "No way as it's a hole in the bottom!", however I see the folks that use them online and they're ponds look so much simpler to keep up with.

    So here is the question: Would you recommend a bottom drain? If so, can you give me a picture or a general idea of layout? I was curious if I were to install one into the liner, how does one do the piping to the filter or settling chamber as I've heard it called? Do you drill a hole in the soil to get to this chamber or do you attach it next door to the pond? I'd love to see layouts of folks' current setups.

    I'M A SIMPLE PERSON. I don't want an overly complex filtration layout. It's not a koi pond, but a water garden with perhaps one or two koi in it. My layout is rather basic. It's a 10' x 6' x 3' deep curvy pond with a small waterfall to help with circulation.

    Thanks for any help!


  2. dweav44

    dweav44 LawnSite Member
    Messages: 51

    If you have koi in your pond then it is a koi pond. I think you are saying that it isn't a 'koi' pond because it doesn't have a traditional filtration system used for koi.

    Are you tired of having to drain the pond and clean it out? Then...

    YES! Bottom drain all the way. It is a little scarry cutting the bottom of the liner, but if done right then no worries. You need to get on a koi forum called Awesome site with MANY helpful people. They can help you with filtration design and many of them can help you build your own DIY filtration system. I don't think you have too many koi for that size pond so you are probably ok there.

    As far as general design goes you typically go for a gravity fed system. Water always finds its level so that is what you are going for here. Not to mention if you can gravity feed it then there is much less disruption to the crap you are trying to take out.

    I recommend to ANYONE building ponds of anykind. You can bet that even if I had a pond without koi I would still have a bottom drain.


    filtration 001.jpg
  3. mngrassguy

    mngrassguy LawnSite Silver Member
    Messages: 2,167

    I've never put a drain in any of my ponds. Just a skimmer with a pump inside it. Much simpler and less chance for a leak.
  4. dweav44

    dweav44 LawnSite Member
    Messages: 51

    How often do you clean your ponds? I have yet to clean any of my ponds that have bottom drains and never will.

    You have to cut the liner to install skimmers. How many leaks have you had in your skimmers?

    Bottom drains are worth looking into people. Plain as that.
  5. biodale

    biodale LawnSite Member
    Messages: 184

    Hell Yes! Never and I mean never make a pond without a bottom drain. Use the Tetra bottom drain with a 3" hole for a small pond. My 5000 gallon pond has one and hasnt leaked in over 10 years. You cant keep a pond clean without a bottom drain. And by the way, use a skimmer also.
  6. dweav44

    dweav44 LawnSite Member
    Messages: 51

    a must .
  7. mngrassguy

    mngrassguy LawnSite Silver Member
    Messages: 2,167

    I see your point but up here in the great north woods I have to clean my ponds every spring to get rid of leaves that sink before they get to the skimmer. It does suck but I can't see a drain helping with that.

    I've never heard of anyone putting in a drain but I can be open minded. I can see that in dusty places like AZ it would be a must.

    Thanks guys, great forum!!!

    Oh ya, leaks around skimmers? Only once and that was enough.
  8. tadpole

    tadpole LawnSite Bronze Member
    Messages: 1,221


    The installation of a bottom drain for a Pond is solely for the benefit of the Pond owner, it is definitely NOT beneficial to any resident fish.
    Although I don't use bottom drains on any of my installs, I do have a few Ponds that I service that have bottom drains. I probably get problem calls twice as often on those with the drains as opposed to those that don't.
    For a bottom drain to work properly you can not rely on gravity. The water must be lifted to either a settlement chamber or directly to the filter. An external drive pump is required for this (some of the newer submersible Mag Drive pumps may work). Using an external pump on your Pond would probably be overkill. Based on your indicated Pond size, you have a capacity of less than 1000 gal., probably closer to 750. The smallest external direct drive pump available is rated in the neighborhood of 2200 gph, which would circulate your pond volume about 3 time an hour. This will create a quite powerful suction at the aperture of the bottom drain possibly posing a danger to any small fish and would greatly ****** the invertebrate population growth which is necessary for a healthy Food Web.
    The addition of a bottom drain will also preclude the use of a gravel bottom, which is also quite important for biological balance.
    I find it interesting that you were referred to (which IS an excellent site) in regards to the benefits of bottom drains. One of the main threads on this particular site is 'Mud Ponds' which ,of course , are perfectly natural and, for sure, do not have bottom drains.
    Will this be a bare liner Pond? Will you rock the interior walls? Will you include planting shelves?
    I would forget the bottom drain idea. It is going to be difficult enough to achieve any semblance of biological balance in a Pond of this capacity without adding an unnatural device that will add to the initial expense but may or may not save you maintenance time.
  9. dweav44

    dweav44 LawnSite Member
    Messages: 51

    I respectfully disagree.

    Those are strong words. Most people put a pond on their property for themselves not for the fish. BUT...
    Bottom drains benefit the resident fish by removing the fish waste and debris that, if left alone, can cause serious hikes in amonia which is very harmfull for fish. Bottom drains are used in bare liner ponds. Within that liner setup there isn't possibly enough natural breakdown of amonia to be safe for fish. The waste is taken away to filtration and removed from the pond water. With this setup there are biological filters that grow beneficial bacteria that helps to control the amonia.

    This is absolutely not true. I have installed a 32,000 gallon koi pond that has bottom drains that are gravity fed 150'to the filter units. Each bottom drain can pull 3,400 gal/hr. The great thing about gravity fed systems is that the debris isn't strirred up before entering the filter chamber or settlement tank.

    You lost me here.

    There are biological filters that do all that gravel does, without the mess.

    Mud ponds are the absolute BEST environments for koi. That is why they are all over Japan for breading. Problem is that not many people want a mud pond in their backyard where they really can't see their fish. In comes the liner pond which brings me back to why we need the bottom drains and biological filtration.

    Ask people on Koiphen. Biological filters create that balance the pond needs. I don't ever want to drain a pond and clean it out. No thank you.

    You will have to excuse me, but I can't handle incorrect information. Especially on a forum.

    Bottom line...I can't stand having to drain a pond(stress fish) and clean it out. I have done it once and I have seen the pictures. There is a reason they don't tell you this or show pictures when selling you the system. Gravel and rocks at the bottom of a shallow pond...beautiful! until you have to clean it.

  10. tadpole

    tadpole LawnSite Bronze Member
    Messages: 1,221

    And I respect your right to disagree. Lively discussion is always eventually leads to what is true.

    Even though they are called 'Gravity Fed', the water is not going to move through the drain without a pump creating the flow. I just don't believe that the terminology is accurate, even though it is accepted in the Pond industry.

    I want to make it clear that bottom drains DO WORK, and quite well. What I have a problem with is that the use of a bottom drain indicates a bare liner Pond which is a completely unnatural aquatic environment. There is no way to approximate a functional aquatic eco-system in a bare liner Pond.

    The primary purpose of a gravel bottom is not to provide bio-filtration, but to provide habitat for a wide diversity of invertebrates that are crucial in the reduction of organic waste and debris to simpler forms that are subsequently used as food by other invertebrates. These same invertebrates form the base or foundation of the aquatic Food Web. Without a nominal invertebrate population, the aquatic environment will never be in balance.

    A 'Gravity Fed' bottom drain system requires that all of the modules (settling chamber and filtration chambers) be located below the Pond's water line. This requires excavation of an area large enough to house the modules and provide access. In Bbentler's case, this required area, to me, is not justified for a 60 sq/ft Pond. A Skimmer and an adequately sized bio-filter will ensure that the basics for water quality are provided.

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