First off the numbers. I test chlorine/PH every couple days to see when the next cup of acid needs to go in. I test the water monthly with my kit and visit the pool store every weekend or two. These are the numbers from today. They are very close to what I usually have. The only number that has fluctuated is calcium hardness. Earlier in the spring it went over 400 for a few weeks before I realized the importance of getting it lower. I have been draining and filling to get it down. Mother Nature has also helped this summer with lots of rain. Whenever I drain the pool I go get the water tested to make sure it is balanced. Pool gets brushed once every week. I bought a wall whale brush when this problem started.
My wife and I went on vacation May 1-12 and our children were supposed to throw a cup of acid in the pool every couple days. That did not happen. We returned to a pool with a PH above 8.2 and CH around 430 or so. Chlorine has never been a problem as we have a SWG. I just adjusted it down as the FC level was averaging 5-6. This is when I discovered the little brown spots. They are brown in color like dirt and a bit stubborn to remove. I started using a stainless steel brush because the nylon brush was not working. I lowered PH to around 6.6 for one night and scrubbed away the next day, raised the PH, and thought with water now in balance I would be done with them. That was 6 weeks ago and today I spent another 15 minutes scrubbing spots.
They only appear on horizontal surfaces. They do not cluster at all and appear completely random around the pool. They are reoccurring but their numbers are greatly reduced since I balanced the water. Iím just wondering what else I might do to stop them from coming back.