18x36 sport pool pump
I have a quick question around pump size. I have an 18x36 sport pool, with 3.5' shallow ends and 6' deep end, with each representing a third of the pool area. We also have a hot tub running off the pump as well. The pump is located approximately 10 feed from the pool and 15 feet from the hot tub. Our calculations for the pool put us at 21,000 gallons, needed 45 gallons per minute. The old pump no longer works, hasn't been running since we bought the house last year and I think is undersized at 3/4 HP. We are getting a new liner installed so I have no experience with how well the 3/4 pump performed.
I am looking at a 2 speed pentair whisperflo. My question is: do we need 1.5HP, or should we be looking at a 1hp?