Hi, I've been lurking around here for a few weeks reading and then did some more reading thanks to mas985. I am in the planning / buying stage of an 11k AGP which will be simi-buried 30". How would one go about figuring head pressure on a pool that is not yet built? I will be using a 120 sf c-filter and I would assume the pump/filter will be plumbed at the pool. Is there a general or average number to use for an AGP for determining what pump is best? I was thinking of using the Intelliflo vs as its rpm range/gpm can go as low as 20gpm which would get me a 10 hour turn over and I am not opposed to a 2 speed. Our electric rate is .12 kwh. I dont mind spending the money on an efficient motor but their is a point of diminishing returns. I've read that its better to have the water circulating for longer periods of time which will help keep the water healthy than to have stagnant water for longer periods. I guess all in all I am looking for a pump that I can have running for longer periods with the least cost to run.