Hi, and welcome to the forum!!

I assume this is a vinyl pool, and I also assume that you're using trichlor pucks for chlorination? I say this because your CYA is so high and your pH was so low--both side effects of trichlor. Honestly, your CYa level is so high that I'm surprised that you're able to keep the pool algae free at this point. You can do it, by keeping your chlorine above 8 ppm at all times, but if you can, it would be worth draining/refilling abiout 1/2 of your water to get the CYA down to a manageable level.

On to your question, though--I would try first shocking the pool, using bleach or liquid chlorine. This is going to mean taking the chlorine up to 25 ppm and holding it there by testing/adding more bleach to get back up to 25. You hold it there until 1)the pool starts to clear, 2)you have zero combined chlorine, and 3)you don't lose any chlorine when testing at sundown and again at sunup. If the cloudiness you're seeing is a precursor to an algae bloom, that will take care of it. Keep the filter on 24/7 and clean the cartridge as your pressure indicates. Even if the cloudy isn't impending algae in the water, it never hurts to give the pool a good shocking after a large party.

What is your calcium hardness level? Do you use any cal-hypo products?

If shocking the water doesn't help, and it's truly just the backwash from the filter, then you might want to try a flocculant, which is designed to make the little fine particles stick together into bigger particles that can be caught by the filter or sink to the bottom to be vac'd up. I am normally not a proponent of flocs/clarifiers, but this year when I started up my new filter without backwashing the dust off the sand first, a very similar thing happened to me, and it took a bottle of clarifier and a couple of days (and a LOT of vacuuming) to get it cleared up.

Hope this helps!

Janet