My wife just called. She tested and TC was less than 1 ppm.
Is that normal when fighting an algae bloom? 20 ppm did not last even 6.5 hours? I told her to add another 9 gallons.

If that's normal, can somebody please calm my fears?
My CYA was at 90, so I cannot believe the sun used up all that Cl (even in HOT Texas...) But, I guess I can imagine it getting used up killing all those little algae critters... right?