I have a 27,000 gallon plaster pool and the stabilizer level was 100 and water was dull/hazy looking. Decided to drain 1/2 of water and replace in order to lower the stabilizer level. Water source was from a lake. After filling, the water was, of course, green looking so shocked with 6 gallons of 10% liquid Chlorine. In the morning the water was a much lighter green and two days later the water was crystal clear. It looked great. The stabilizer was now 50. About a week later, the water started looking dull/hazy again. Checked the water and found the PH at 7.8, TA=130, Hardness=250, Free Chlorine=2 (a little low), Combined Chlorine=0, Stabilizer=50. Added 3 gallon of liquid (10% Chlorine) right away to to shock in case the hazy/dull look was due to start of algae. Decided to lower the PH using liquid acid. Added 16 oz and checked level about 5 hours later. PH was 7.6 and Total Alkalinity was 120. Added 8 more oz. and checked next day; PH was now 7.4 and Total Alkalinity=110. Chlorine was above 10 PPM. Water was still dull/hazy looking. Let DE filter run for about two more days but water wasn't looking any better or worse. The water level had become low so filled with well water which I have used in the past without problems). Came out in the morning and water was now very cloudy (not green, just cloudy and can't see bottom in 8.5 ft deep end). Chlorine had dropped from 7 PPM to 1 PPM overnight. Ph=7.2, TA=110, Hardness=250, CYA=50. It appears that adding the well water really exasperated the hazy/dull looking water and my Chlorine level dropped a lot overnight (i.e., 7 down to 1 PPM). I just added 5 gallons of 10% liquid Chlorine and the DE filter is running fine. I don't see any DE sitting on the bottom of the pool like when I've had an issue with a damaged filter grid before. Looking for some guidance on what I might do to clear up the cloudy water now (is the cloudy water (not green) some type of algae or has something precipitated out of the water to make it cloudy. Thank you.