I just got off the phone with Hayward, and the tech guy I was talking to thinks my pump is too big for my system and my lines too small. He was a bit surprised that it has been working since 2007 without failing (working too hard to push the water through the 1.5 inch lines???)
Here is what the pool store did back in 2007. Hayward Tri-Star 1HP pump SP3210EC Single Speed, 2" line from the skimmer then it all goes to 1.5 inch including back the returns (if I had known back then (i.e. if I had been a troublefreepool member) I would have demanded 2" for everything). The sand filter is 3.14 sq ft with a design flow rate of 63gpm. When running, the pressure gauge shows 22psi and it bumps up to 26 when the solar is on.
Would it help for me to change all the lines in the pump house to 2"? The lines going to the returns will still be 1.5" and so will the suction cleaner line. The other thing I've been considering is a cartridge filter, and the guy at Hayward said not a bad idea as they can handle more flow than a sand filter. I was actually looking at the Jandy CL460.
The last picture is the performance data for the Tri Star line. The 3210EE just a newer model number for my 3210EC. If I'm reading the chart right, even at the max 70 feet of head, the pump is putting out almost the maximum my filter is designed for???