I need to replace my leaky 72 sq ft American Products stainless steel filter. I have a 40,000 gal pool (maybe a little bigger) with a salt system. I am thinking that this might also be a good time to replace my single speed 2hp whisper flo with a variable speed or two speed pump to save on electricity. The local pool store said Hayward is the only manufacturer that makes a 72 sq ft filter and this size is being phased out. He recommended that I just replace it with a 60 sq ft unit. Would a 60 sq ft filter work as well as a 72. I am worried if I downsize the flow rate wont be as good. Would this also effect the time it takes to heat the pool? Any advise would be greatly appreciated.