I have been learning from tfp for 3 seasons now and thanks to all the great help that has been provided I have not needed to post anything until now.I bought a forclosed house summer before last, came with a pool that looked like the creature from the black lagoon lived there, it was a black nasty mess, we actualy had to empty it, scrub it and refill it. Of course there was no pool equipment, they took it with them when they left. With a tight budget I bought the 3/4 hp pump and a Hayward C500 Star-Clear 50-Square-Foot Cartridge Pool Filter, the flow rates listed calculated them to be adequate, also the plumbing was all 1 1/2 in pipes too. After the fist summer of cleaning the cart every other day, daily if the pool got dirty, and having very little flow from my returns I decided to upgrade to the sand filter in my signature and upgraded all the above ground plumbing to 2 in pipes.
After doing this, the flow from the returns were better, not great but better (later found out that I needed eyeball fittings on the returns, there where none to begin with). The flow was better now but I could not get the pump to prime fully, it would only prime about 3/4 of the way and I would get tiny air bubbles out of one of the returns, but for some reason only one. I checked all the o rings and connections and could not find any air leaks, I replumbed the above ground plumbing 3 times trying to fix it. Eventually summer ended and I closed the pool.
Now I have reopened it this year and same issue, I was thinking maybe an under ground pipe leak, but it gets air in the filter no matter if I run the main drain, skimmer, or both. Was even considering building a pressure tester, but today I bought a leaf eater vacuum and decided since my pool does not get much sun and is hard to keep heat I did not want to use the garden hose to use it. So I built anadapter to connect it to a return instead. After I connected it I was not getting enough pressure so I decide to close off my other 2 returns. Turned my pump back on an all of a sudden I am getting near full prime, still a small air bubble at top of lid but no more cavitation like before. The filter pressure however went to 20, usually sit between 0-5, 0 right after backwashing. Any idea what is going on? Is my pump maybe to small, or is it pumping the water faster than it is pulling it in somehow?
Sorry for the long story but wanted to give a full picture of the issue, let me know if more info is needed.