Just finished the SLAM & its all looking perfect on all the levels.
About a month before the SLAM (2 months ago) I added CYA & it was at the upper levels 80-90.
Tested it again & its <10!
I've only done about 3-4 back washes, but they're only <2min & probably lost about 3" of so of water level all up.
I thought high chlorine might throw off the test, but we're back down to FC: 6 & there's no CYA.
How have I lost my CYA?
(test kit is <1 month old)
I'll grab some more, but i'm hesitant to pop more in - in such a short time frame.