Bottom Drains
Why install a bottom drain ?
For the first 3 years of my ponds life, I didn't have a bottom drain. Leaves and other debris which got by the skimmer would have to be removed with a net, which was a back breaking chore. Black muck (mulm) would accumulate on the bottom of the pond till it was 6" deep. When fish stirred up this muck, Nitrogen bubbles would come to the surface of the pond and lower the dissolved oxygen levels. Now that I have bottom drains, the bottom of my pond is completely clean. The drain removes everything except rocks.

How does a bottom drain work ?
Animated Bottom Drain
Using Gravity !!! When the pump draws water from the settling chamber, gravity will force water from the pond through the pipes and back into the settling chamber. Water always wants to seek its own level.
Should I consider a bottom drain ?
YES, every pond should have one! If your are looking for a low maintenance pond, I would definetly reccommend a bottom drain no matter what size it is.
A drain in the bottom scares me! Wont it leak ?
Not when done properly! We have over 20 of my DIY style bottom drains in use at Bickal Koi Farm. None of them leak. Most commercially sold bottom drain units require you to bolt a flange to the rubber and require silicone sealant. My DIY style drains require NO SEALANT! So there is no possibility that the sealant can fail in the future!
Im going to put in a bottom drain, but how many ? how far apart ? flow rate ?
Flow rate depends on the size of the drain. A minimum flow rate of 1000 gph for a 4" drain. How many and how far apart depends on the shape of your pond bottom. If your pond slopes to one central point you may only need one drain. If you have a completely flat bottom, you may need several, spacing would be dependant on the flow rate.
Can I connect my bottom drain directly to my pump ?
Yes, you can, but I wouldn't do it. Your pump would get clogged every hour. A settling chamber is much better, because it allows the bigger particles to settle and not clog the pump. It also provides a safe haven for little fish that swim into the bottom drain.
Can I build my own bottom drain ?
Commercial vendors offer several models of 4" bottom drain that can be purchased from
$89 to $129 dollars. However, you can build your own for less than $15.
Step by step instructions are available on my DIY CD.