I'm new to this site and I really like what I've read so far. I'm having a major pain trying to get my pool started up this year. I've had many issues, but the one I have a question about is: My pump is losing suction after running only for 10 minutes on filter. It runs just fine when on recirculate, it never loses suction. The pump doesn't lose prime and I[m not seeing any air bubbles in the pump. (if there are air bubbles they are very tiny) I'm not sure if air bubbles are coming out of the return, cause I've added so much stuff like Floc and Clarifier and Agaecide etc that I don't know if the water is just bubbling up cause of that or air!!! When I first turn the pool on, the water comes out the return really hard, but then after 10 minutes it trickles down to nothing. If I put it on recirculate it continues to come out really hard and never loses pressure. The Pressure gage doesn't increase while the water is decreasing out of the return. I've backwashed many times and it doesn't help. I've checked the o-ring on the pump basket and I've cleaned out the filter and latterals (just in case). I don't understand why the pump works fine on recirculate but doesn't on filter. The pump and filter are brand new. Some of the plumbing is new and some is original to when the pool was installed. Before I go and buy more pvc flex pipe and fittings and rehook everything up to try to fix any possible air leaks, I was wondering if there could be another cause for this happening. I've already gone through hooking up twice cause I first replaced the filter and then the pump went out so I had to then hook that up. So I've already wasted a lot of money on PLUMBING. Also I tried to vacuum today just to see what the pump would do, and after vacuuming for only a minute or two the pump does lose it prime and I lose all suction in the skimmer.