CYA is denser than water and settles to bottom of pool when left unstirred.
He said leave the pool off for a day or two then
close the skimmer drains and pull all the water from the pool bottom when you do normal backwashing
(or you could use Waste setting when you have too much water in pool).
So I needed to backwash, so I added a couple inches of water. CYA was at 120.
Then Left pool off for one day. I closed skimmer drains
and pulled about 3 inches of water out via the bottom drain. CYA went to 80.
It then rained two days later and I needed to lower the water another inch or two.
Not wanting to backwash the new Diam earth , I
set the pool to waste, closed skimmers again. Lowered pool about one-two inches.
CYA is now 65. Unbelievable. This is using my kit to measure.