Hope someone can help with this one, makes no sense at all.
Just opened inground pool 1 week ago (its about 17 yrs old). Ran pump continuously. 3 days is a row, got up in the morning, water level had RISEN a few inches.
Backwashed to drop level, watched level and it still rose. Turned off pump for a night, next day, level had dropped about 1/4 inch. Ran pump, level rose again. Turned off pump for another night, next day level had dropped much more - about 4 inches.
So I plugged up the returns, one at a time and watched the level, still dropped. Next I plugged up the skimmer, still dropped. Which leaves the main drain (can't plug it up to check it, water cloudy and cold otherwise I would cover it with plastic and a sand bag).
I'm thinking maybe there is a crack in my main drain piping and it's sucking in water and blowing in thru the returns when the pump in on, and it's leaking out when the pump is off. But, if so, why didn't I lose water over the winter?
The only other reasons I can think of for the water loss is a problem with my backwash valve causing water to leak out of the backwash hose end just above the ground (the area where the water comes out when I backwash), but it's hard to tell since the ground is saturated already from all the backwashing I have done.
Also I have had a problem in the past with my main drain where a small twig got stuck in the extra valve/opening in the main drain (don't know what its called)that let water out (I had to dive down, remover the cover to check this). Again, don't know if this could be the problem, can't dive down quite yet.
Still doesn't explain the rising water if one these could be the problem.
Hope someone can help! Thanks!!