This forum is awesome. I want to start by saying thanks to all for the questions and the answers... I've learned a ton. However, I do have a question. Last August we had a 17K - gal Fiberglass ig 15 X 34. We have a 1.5HP Hayward Tristar with a Hayward Perflex DE EC40AC. Plumbing is 2" from a single skimmer to the pump,thru the filter, heater, SWG and then into a manifold where it goes down to 1.5" to a total of 6 returns. I've noticed that the pump always sounds like it's working hard and the flow out of the returns isn't very strong. After cleaning the DE fingers per the "Stickey" about cleaning a DE filter, and adding DE, the starting pressure is about 14lbs. Still not much flow. Does this sound like my pump is too big and/or the filter is too small? How can I calculate what I need so that I can validate the equipment I have? It seems odd to me that the pump requires a min of 2" pipe, but the first thing it does is get reduced to 1.5" at the base of the filter and out of the filter it goes from 1.4" back up to 2". It seems to me you would want to remove the restrictions....