Water gets cloudy for unknown reasons - frustrated!!!

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.:mad:

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

Did you find CC when you tested this morning? 2.5ppm FC is just below the Best Guess Chart minimum for CYA 30. Maybe it's the beginnings of a bloom?

Big Dave,
Unfortunately I didn't check the CC this morning and I've already added enough CL to bring it back to 15ppm.
I know 2.5ppm is on the low side, but it could not have been there for long since it was 5.5ppm just 24 hours prior. It just seems like my water is over sensitive to becoming cloudy.

I'm looking for any guesses.

Cloudy is something in the water, maybe precipitate, maybe algae. Since it goes away at shock FC, I'd guess algae. I'd expect some CC if it were algae - that's why I asked. Perhaps move the low target up a bit to 4ppm FC after this shock is complete? When you've shocked did you maintain shock level for a day after the finish line?

Your pump is way over-sized for your pool. I wonder if because of that, you are not filtering things out well and instead just blowing everything through the filter back into your pool. This may not be it, but just thought I'd throw it out there.

Watermom,
Actually I made an error on the HP size. It's a 1HP motor, not 1.5HP. I don't really think that is too bad for a 300 lb sand filter, but what do I know.

Big Dave, yes I held it high (1 day) after the water cleared and I did an overnight FC test to confirm that the CL was the same in the morning as it was the night before.

Another idea I'm having about why the water got cloudy again--- When I shock my pool, I keep it uncovered so I don't kill the solar cover. My cloudiness came back two days after covering it again because the WX has gotten a little cooler. Wondering if I'm dragging contaminants back into the water from the cover? So this time I'm going to shock with the cover on. Not good for the cover, but I'm hoping that if contaminants on the cover are a problem, then I will kill those in the "shock" water.

1PM EST update: I put enough CL in about 5 hours ago to bring it up to 13PPM. I just checked it and FC is at 13.5PPM and CC reading is 0.
What does a CC reading of zero really mean at this point?

Also I did just add a bit more CL so it should get to 16PPM. I'll test again in a few hours.

You're right. A CC of 0 doesn't mean a whole lot right now. Some CC could indicate that the chlorine is working on something in the pool but the absence does not tell us there's nothing there.

6/5 7AM: This morning the water is clearing up. I have not added any additional CL since 1PM yesterday 6/4 when I set my CL to 16ppm. As of this morning 7AM, my FC is holding at 15ppm and CC 0.5ppm. It's kind of odd to me that the pools isn't really consuming much CL, but the water is clearing.



Historical:
6/4:1PM EST update: I put enough CL in about 5 hours ago to bring it up to 13PPM. I just checked it and FC is at 13.5PPM and CC reading is 0.
What does a CC reading of zero really mean at this point?

Also I did just add a bit more CL so it should get to 16PPM. I'll test again in a few hours.

You may not be adding more chlorine, (and it doesn't sound like you need to) but you are running your pump and letting your filter do its job which is to remove stuff from the water. Thus, it is clearing. I would run it pretty much 24/7 while you are trying to clear it up. After that, you can cut your run time down. Glad to hear it is looking better!