A buddy of mine just moved into a house with an inground vinyl pool.
DE filter... Pretty typical plumbing.
He gets tons of air in the pump basket, his pressure is very low... After running the pump for a few hours the pressure goes down to almost zero and almost nothing comes out of the returns. When he backwashes it goes up to about 10 and then comes down again.
He did the bucket test with the filter off for 12 hours and on for 12 hours and the pool does not appear to be leaking at all. (Unless the test wasnt done long enough)...
Any suggestions on where to look if there is no leak?