If you are dropping 8# pressure, from cleaning, then you are gathering quite a bit of stuff on your filter. Will it clear the pool? Dunno.

If your dirty filter pressure is only 12 psi, your pump is not badly over sized for your filter. I'd still recommend a new cartridge - it may not work better than the old one, but if not, you still end up with a spare, so while one's cleaning the other can be filtering. And, if it DOES filter the fine cloudy stuff better . . . well, there you go!