After any water from inside the tub drips on the outside it leaves white spots everywhere after evaporating. Obviously it's solids from the tub water, but does anyone know which solid it is?
At first I thought it was calcium, but my calcium levels test normal and when I sprayed water from the hose I use to fill the tub onto the panels it didn't leave the white residue.
Then I thought it was the aromatic salts I add every once in a while, but I stopped using them completely and the residue remains.
So is it chlorine, non-chlorine shock, the borax I use to raise pH, or all of them combined? If so, I assume there's nothing that can be done, correct? I use 303 to clean the panels regularly, but it doesn't do anything to prevent or reduce future spots.