Hey,
something very similar happened to me with a 3/4hp hayward pump and 50sq cartridge filter. all the skimmer baskets and the cartridge was clean and all valves open and pump was primed but still seriously low suction, no air bubbles came out of returns. after a couple days of very slow and low suction/return the pump started to make a ton of noise not 2 long after that the pump died completely and wouldnt even turn on anymore. i hope your problem is not serious though because a new 1hp hayward maxiflo pump fixed it but cost me $218+install time everything works perfect now. Good luck
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