Measured CYA with two methods. Taylor test in TF100 kit and Pentair stand alone “Rainbow” test kit.
Taylor showed 65-70, Pentair 90 ppm before I raised the SLAM chlorine amount.
I reduced CYA by draining roughly 1/3rd of my pool and refilling with city water. It was dropping from 110 to 100 due to on recent Heavy rains over the past few weeks. (All previous tests until this week were done With the Pentair kit, it’s quite easy but takes much more reagent than the Taylor).
Some of what’s on the bottom might be debris but it clearly changes color from mustard yellow to dark brown at some point. Plus, we’ve never seen this yellow algae before. We’ve had green algae in the past but only rarely, maybe once annually.
Typically, the yellow algae starts small...Like tiny “dots,” then those coalesce into a blob-like form after a few hours of growth. Later, over 6-12 hours, the chlorine in the water kills it and I vacuum it up. It doesn’t move, it must be brushed or vacuumed....and is almost always in the same or close to the places.
BTW, the dichlor pucks have already bleached the liner pretty bad below the waterline. I’m going to keep this level as long as I can to kill this outbreak.
Did a full bottom and sides brushing before I turned In tonight. If anything was growing on the bottom it’s in the Chlorinated water now.