I have an above ground pool that is 16 x 20 with a bottom drain. It started leaking two summers ago about an inch each day. I have never found any wet spots in the yard around the pool. Ive tried finding the location of the leak without any success. When I opened the pool this spring it was completed drained which leads me to believe its in the drain somewhere. I refilled the pool and left the bottom drain closed. This still didnt solve the problem. In fact, once I opened the bottom drain it seemed to lose less water than when it was closed. It iss still losing water daily. I know the water loss isnt from evaporation. Any suggestions?
Water Leak
- Thread starter Herr
- Start date
Welcome to tfp, Herr 
It is surprising that your liner is still functional since allow it to drain almost always requires replacement, unless the drain was short and the liner was almost new.
There is a good article in pool school: http://www.troublefreepool.com/pool-school/leak_detection, but if it leaked down to the bottom, then it is likely your leak is at that level. I would guess that it is the drain or drain line and when the pump is running the vacuum created prevents water from leaking out and when you shut it off, then the water is able to leak.
It is surprising that your liner is still functional since allow it to drain almost always requires replacement, unless the drain was short and the liner was almost new.
There is a good article in pool school: http://www.troublefreepool.com/pool-school/leak_detection, but if it leaked down to the bottom, then it is likely your leak is at that level. I would guess that it is the drain or drain line and when the pump is running the vacuum created prevents water from leaking out and when you shut it off, then the water is able to leak.