Koi Pond Bottom Drains

   Two bottom drains should be considered for ponds over 2000 gallons.

    Between liner & drain, use GE II 100% silicone - available at your local hardware store 

To keep dirt out of drains during plumbing installation, plastic covered cardboard & tape was used. This was removed just before  rubber liner was lowered into place. 

4" Bottom drains are easy to install. Consider using cement under and around the drain after installing to firm up the drain area. This benefits in no settling once the pond is completed. Cemented in bottom drains are very important for the aerated models. The pipe below could break from stress if it is not cemented.

Many pond builders install a swing type check valve prior to the pump to aid in keeping it primed. Consider installing a 3-way valve and run the skimmer line & bottom drain to this valve. This permits controlling the percentage of water coming from the bottom drain and from the skimmer. Perhaps you need to increase the flow from the skimmer during Fall when leaves blow into the pond... Nice advantage to keeping the surface clean!

Aeration dome bottom drain tips:

Multiple air lines: When running air lines to the bottom drains. Be sure to run separate air lines to each bottom drain and only connect them above the ground outside the pond. If the T that connects them is below the ground or under the pond liner, it will be tough to force water out when pressurizing the air line. If this happens, the following tip may help.

Water in the air line: If you connected then with a T below the pond liner and one of the domes is not releasing air, follow these steps. 1) Turn off air. 2) Put several large rocks in a 5 gallon bucket that has a rope tied to the handle. 3) Fill the bucket with water and lower into the pond. 4) Rest the bucket on top of the dome that was working to block air disk. 5) turn on the air pump. This should force the air to push out any water inside the line and make the other dome work. When the dome that was not working begins to release air, wait a minute to be sure all the water is out. Then remove the bucket to view that both aeration domes are working.