I have been developing these mystery stains all over the bottom of my pool. They do not brush off, they do not feel raised or rough. The only thing I can think of is that the ph was allowed to get high (for me anyway) and remained above 8.0 for a while (not sure how many days). The chemicals were checked weekly and brought back to normal. But I am realizing the ph climbs faster than weekly . The TA never got over 100 at any time and hovered around 90. I have been adding acid every few days to keep it at 7.4 to bring the TA back down . It is currently at 80 and being carefully monitored.
FC: 11 (I have been raising this with the SWG just in case this is organic, but it doesnt appear so)
PH: 7.4 - 7.6
TA: currently at 80