Wrong cya level for shock

[Senahnayr]

Hey guys and gals,
I had a pretty green pool again this spring and have been slamming based on 40cya and trying to keep 16 fc overnight. I'm still not real confident in these cya tests. So I've been at it for 5 days and I decided to retest my cya and now I'm getting 20. Done it a few times over to make sure. My question is if I should try to get to 30 cya and maintain the overnight 1 ppm loss at that level. Based off of my 40cya assumption and going to 16 ppm I haven't dropped below 11fc at all and the pool is pretty clear.

Thanks for any help once again

 

[Senahnayr]

Actually I lied, it hasn't been under 11 in the past 2 days

 

[IceShadow]

The OCLT is typically done at SLAM levels but that's more of a guide than a requirement. You can do it at whatever level you want, so long as it's high enough that you can notice any drop. (If your CYA is down at 20-30, you will want to lower the FC accordingly though, because you don't want it to damage your pool equipment/finishes by being too high for the CYA level.)