Last fall before closing I thought I might have a leak, since I seemed to have to top off the pool water more frequently than in past years. Yet that need seemed erratic. Did the bucket test several times, and did not get consistent results. Before closing, I squirted dye around the most likely areas and did not notice anything. I suspected the leak might be in my skimmer return line, and figured that would be easy to tell once I lowered the water level.
Over the winter, it has become clear that I have a leak - and that the problem is not (or at least not only) the skimmer return line. But the leak is slow - about 1/16" per day, and thus very hard to detect in an overnight bucket test. but clear over the course of weeks. In my pool, that's about 25 gallons per day.
My guess now is that the problem is in the bottom drain return line. I say this in part because I can't think of other options. But also it seemed to me last summer that I didn't notice a drop in water level for a while after heavy rains; the rise in the water table might have kept that pvc return from leaking.
The deep end of my pool is about 8 1/2'. I can't imagine digging to try to gain access to that return. But I don't think my pool water will circulate very well If I just cover the bottom drain and close the return to the bottom drain at the pump.
So what to do? Should I just live with the leak, monitoring water loss to be sure it doesn't increase? Or do I really need to cover my bottom drain? Is there another alternative?