We have an Intex 18' x 52" Ultra Frame Pool, approx. 8400 Gal. - This is our 2nd summer with it in AZ. Last summer we had relatively few issues, but this summer has been quite different. We had what I believe to be Mustard Algae appear in June, and tried repeatedly to get rid of it through shocking methods listed on TFP with little success. We shocked, and brushed like crazy, but it always came back almost immediately. We were out of the country during July, Monsoon season here with a lot of dust and rain, and came back to a bigger mess. Nothing seemed to work, and we couldn't keep chlorine in the pool, even after adjusting CYA just above 50. I could add 2 or 3 gallons of 10% liquid and it would be gone in less than 24 hours. Finally, since we own a pump, we decided on Monday to drain and refill. We drained down to about 4 inches, treated all hoses, equipment, pump etc. with a bleach solution and refilled. The material re-appeared on the bottom before it was even 1/2 full. We added chlorine(Liquid 10%) as we filled, and added conditioner to get CYA back up. Pool was filled last night, I shocked again and chlorine was off the charts this morning. I tested again this afternoon, and I am at approx 2ppm. Seems like nothing has changed. I seem to be fighting a losing battle and will take any advice to try and get a handle on this. I am attaching a pic, in case it may help.
CYA - 45
FC - 5ppm and dropping fast