Water gets cloudy for unknown reasons - frustrated!!!

[myLABSpool]

I'm totally frustrated and nearly ready to give up on my pool. Even though I maintain my CL by using liquid (12.5%), the water gets cloudy from perfectly clear way too frequently. I'm now on my second round of cloudy water in two weeks.

My last bout a week ago with cloudy water, I shocked with liquid, holding FC around 15ppm until the water was super clear and the pool consumed no CL overnight. My CYA is 30, pH 7.5, TA 80. (I've really seen no or maybe a max of 1ppm of CC at any time.)

This past weekend, while the water was clear I put new sand in my filter and inspected the laterals for cracks and found no issues. I replaced the seals on my multiport valve (it was leaking a little). The water stayed perfectly clear through the weekend.

I tested the water yesterday morning and the FC was 5.5ppm and the water looked fine. I go out to test this morning and the FC is 2.5ppm (which I think is okay for my cya level) and I peak under the cover and can barely see the bottom.

I'm smoking hot because now I'm going to have to keep the solar cover off, lose my heat and spend dollars shocking again! I'm ready to dump all the water and start over.

Please help.
Thanks

Stats
24K IG vinyl pool
300 lb sta-rite sand filter
1.5 HP pump
CYA 30
pH 7.5
TA 80
Testing with FAS-DPD
Solar cover when not in use
Water source is municipal