Hello TFP, I have a 20 x 40 36,000 gallon in ground pool, 1.5" plumbing, 1 HP Pentair pump, and 3.1 sq. ft., 62 gpm flow rate Hayward sand filter. Also a pool heater. Would like to replace pump and filter with variable pump and cartridge filter. Pump is 6' from edge of pool, which has 2 skimmers and 2 returns, not sure how deep the pipes run. Straight line from pump to center drain is about 16 feet. From pump, it's about 18 ft to skimmer 1, 60 ft to skimmer 2, 30 ft to return 1 and 45 ft to return 2, going around corners (not straight line). What's the best pump/filter combo to move the most water with the existing plumbing? Thanks!