Quote Originally Posted by PRB
I have a Hayward Perflex EC75 filter and a Superpump 2 HP pump. The pump is new, replacing a 1.5 HP pump. My inground pool has 30,000 gal. I get good flow into the pool for about 15 minutes, then it drops almost to nothing. I've completely cleaned the filter. The poor flow happens with the filter has no diatomaceous earth or has the correct amount. There shouldn't be anything clogging the inflow or outflow, and if there was it seems I wouldn't get good flow at all as opposed to poor flow only after 10-15 minutes. The pressure in the filter builds up quickly and is likely limiting the flow rate. Bumping the filter helps only briefly. It doesn't seem like the air release valve on top of the filter would be an issue, as it probably is functioning fine and any air likely would just get pumped into the pool anyway. The pool water is dirty (I am just opening the pool now and am still killing algae); would this lead to pressure buildup in the filter (it doesn't seem like it, as the filter is clean). I had similar problems with the 1.5 HP pump, and thought that a stronger pump might help (it didn't). Any thoughts or suggestions?
I have the EC-65.
I'm pretty sure you have some restriction on the suction side. First thing that comes to mind is, can you see the main drain and that there're no leaves or other debris piled up on it? Happened to me until I could see the drain, and what was happening. Same symptomes. Likewise are your skimmer baskets clean?

The next thing that comes to mind is your comment about recently upping the pump's hp. What size are your lines? 1-1/2" plus head losses along the way may be adding up to the restriction killing your prime with the new pump.

How old are your valves in those lines? I had a recurring problemn with losing prime last summer because the three-way attached to the pump basket turned out to be really poorly designed for efficient flow. I replaced it with a Jandy and it made a huge difference.

Chuck