Tetra Retro fit Bottom Drain
Since my pond was planned at 4 feet deep I knew I needed a bottom drain to suck out debris from the floor of the pond and to help maintain water quality. I had read about installing permanent drains with 4″ tubing and how to cement them in place and had overcome my fear about a bottom drain leak.
However, after hitting solid rock and getting really tired of digging I decided to use a retro fit drain instead. This sits on the bottom and has a 2″ pipe which goes from the inside of your pond, over the edge, to the pump . Of course I made a couple of mistakes when installing.
The directions said to fill the body of the drain with concrete to weight it down. I did not have concrete so I used sand. I then glued on the cap as instructed. It floated. There was more air than I thought even with the sand. So i drilled two small holes and added water until it wouldn’t hold any more. I then had to fill the holes and cover them so the water and sand would not leak out.
The second mistake is assuming my walls were 90 degrees square to the bottom. More like 110 degrees so when I test fit my plumbing it stuck way out into the pond. I then decided this would not work and purchased a few feet of non-kink pipe so I could bend it where I wanted it. Now I have this ugly pipe coming over the side of the pond that I had not planned for.
To fix the ugly pipe issue I purchased another bulkhead, barbed fitting and more PVC threaded parts and elbows. Installing a bulkhead near the skimmer after the lining has been burried and fit to the skimmer was a bit of a challenge.
In the end it all worked out but you can see the piping leading to the drain. In time I am sure this will be covered with “pond patina” (aka Algae). I think I can also use the bulkhead with a pool vac once a year to do a thorough bottom cleaning.
One other design flaw which I am not sure there is a way around yet. I ran my piping from the Skimmer and bottom drain through valves into a wye which then feeds the pump. If my water level drops below the skimmer I lose syphon. I can close the skimmer and keep it going but I think I may need to add a backflow/check valve or a shut off device on the skimmer in case of sudden water loss.
UPDATE: I later changed the plumbing from skimmer and Bottom drain to a simple 3 way valve near the skimmer. I do plan to add a pump to the skimmer
at some point. My next pond will have a proper 4″ bottom drain going to an external settlement chamber/filter.
