I have a 35,000 gal (yes, i'm certain of the size, everyone asks.) salt water pool that over the past two weeks has slowly gone from a little cloudy to very dark. I routinely put 4 capfuls of pool perfect + phos free in the skimmer weekly, and shock once a month or if the chlorine tests low. The weather has been very hot, 110+, for several weeks. It finally rained last night and has cooled off some today.

I went to the local pool store to get the water tested and the results were:
FAC 4
TAC 4
Ph 8/2
Total Alkalinity 120
CYA 45
Salinity 3,400

They didn't see anything wrong with the water except the Ph being slightly high, which is normal for this area. They suggested 1/2 gallon of muriatic acid (will add tomorrow). They said even though the chlorine is normal, I should add 1lb of shock to try to kill what ever is making it cloudy. And vacuum it. They didn't think it was algae because the sample was clear.

I have vacuumed it several days in a row and it always has a coat of something all over the bottom and sides again by morning. I have left the pump running constantly with 100% output for 3 days straight now and no improvement. I can not see the bottom of the deep end and the shallow end looks very cloudy. I just added the shock they suggested a few minutes ago and noticed what looked like flecks of dirt coating the top of the water. When i skmmed my hand across it, i could tell that it was little bugs. It looked like yeast does when you sprinkle it on water.

Any thoughts on what could be going on?