My Hot Springs spa uses salt/chlorine generation and is usually self-maintaining.
Last time I checked, the TA was 71, pH 7.5, TCL 5.1, FCL 4.6.
Then I got lazy or busy or something and didn't check for 3 weeks (my bad).
Yesterday opened the spa to see white filmy scum on the top of the water and strands of the stuff at the bottom.
Water check showed TCL and FCL off the charts high, pH 8.3.
I'm planning to drain, clean and start over. But I am wondering what the white scum could be?
Whatever it is, it can withstand very high chlorine levels.