Yesterday I noticed my pool water did not appear as crystal clear as it had Saturday, and actually got worse through the day. Later I noticed the area of my concrete where my pool blaster vacuum was removed from the pool and leaked water, was now dry and left a powdery residue on the concrete. I went and looked at the pool blaster and it too had a dry white substance left behind from the water.
What could this be? I had recently completed an ascorbic acid treatment but have had my chlorine holding for a few days. I did add some stabilizer to the pool skimmer.
I did the overnight FC test and I think I'm good. Last night was 5.5, and this morning was at 4.