Started shocking with Cal Hypo on July 3rd. Yeah, I was real popular on 4th of July. It was green and cloudy so nobody was going swimming anyway. Had FC up to 18.5 (with CYA around 45 at that point) and it held overnight, so I let it come back down. The green went away but the cloudiness never did. I've been brushing twice a day and backwashed a few times. After a week I could almost see the bottom drain again and then the green started to come back. I never let the FC go below 6.0. While vacuuming every square inch of the pool yesterday, I could tell it wasn't dead algae, which sucks up like dust, but still growing, requiring me to scrub hard with the vacuum head. I'm guessing mustard algae from reading other stories. It will kick up a green cloud if you brush it, and it loves the shady side, slightly more than the sunny side. You can see big green swirls on the bottom where the water circulates. Funny thing is the FC level has been holding overnight since this problem started. I've been testing morning and night, before and after the sun hits it. It loses 3-4 ppm FC during a sunny day.
Anyway, looks like I need to shock again. CH is low so I can use Cal Hypo. pH is on the high side so I'm guessing I need to bring it down. I read not to trust pH readings while shocking, and CYA readings when it's cloudy, so what to do first? These numbers should be good as they have been consistent and responded as expected when adding chemicals, regardless of the cloudiness.
FC 8.0 (this morning, will be 4-5 this evening but I knew I would be shocking)
I plan to add MA first to bring down the pH. Pool Calc says 2 quarts to get to 7.0. Can I add it all at once? How long to wait before hitting it with Cal Hypo? Test again or just shock it?
I plan to use Cal Hypo to get the FC up to 24, brush it and check FC tonight, check FC and brush it again in the morning, then run the power cover over it to keep the sun out. Probably uncover it in the evening, test FC, brush it, etc. etc. How many days of this am I in for? I'd like to think we can swim next weekend but the math ain't working out.
Any other suggestions?
If this doesn't work, 27500 gallons = 136 cubic yards, of dirt that is. Here's a handy volume converter:
Thanks for any advice.