Hello all. i'm having a heck of time. i'm trying to help my sister who has an anthony/sylvan plaster pool, with 2 skimmers, 3 returns, and 2 main bottom drains.. the problem is that when the main drain valve is working, there is NO pressure coming back through the system, but when i turn the valves to only work via the skimmers, pressure is FINE. The problems only seem to arise when i have isolated the main drains at the bottom of the deep end.
Questions - 1: there are 2 main bottom valves in the deep end? Is one a return and other inlet valve? 2: can they be clogged with hair and such? i cannot see any leaves or visible materials. 3: can i actually go down in the deep end and service these main valves with the water in the pool?
I am pretty well versed as i have my own inground pool, however i do not have main bottom drains, i have a side-wall set up.
any advice is appreciated!!