How low is too low CYA for slam?

toddclare

Gold Supporter
Jun 23, 2024
77
Atlanta, GA
Pool Size
21000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Had another post about partial drain and slam, but felt this was a different topic. I did a partial water replacement and thought I ended at a 60 CYA and am 2 days into the SLAM assuming 60. Finally got some real sun and turns out I’m at 50 (dot visible at 50, hidden at 40).

Re-ran the CYA test isince my overnight levels dropped only slightly but the daytimes are plummeting. At 60 my intent was to leave it at 60 for the SLAM then bring back to 70 after.

Now at 50 my gut is arguing. Is 50 better because it’s less liquid Cl versus that’s too low and the CL will Burn off so fast? Should I bump it to 60 or keep on at 50?

I just want whatever it is in there (clear water with higher CC and failed OCLT) to die a miserable death.
 
With an LC pool you'd be targeting 30 CYA . :)

*possibly 40 or 50 in the insane UV part of the year, but its only mid May.

The higher FC target is more detrimental than the UV buffering the higher CYA provides or we would be having everyone slam at 50 to 70.