Effects of Slamming with incorrect CYA

[Bvacchiano]

Helping a buddy SLAM his pool. I measure CYA at 60 he insists it’s 70. His pool, he wants to use cya 70 so we will slam at 28 FC. Anyways, my question is , at the high FC levels of a Slam will the FC fall to the Slam level? Example: nighttime we measure 28 FC we wake up early morning and it’s 24. Is that actually a FC loss or is that just the FC falling to the “possible” slam level of 24 because CYA is actually 60 and not 70? Another way to put it. No matter if I’m HIGHER than Slam level should the FC stabilize overnight even if I’m higher than the actual slam level??

 

[ajw22]

Use the higher CYA and FC level.

CYA measurement is not that precise. If your CYA is really 60 and you are using FC of 28 the SLAM process will work just as well.

 

[henryforever14]

The only two things that cause FC drop are sunshine and organics. CYA protects FC (to some degree) against sunshine. If you SLAM higher than what your CYA indicates, you will lose FC faster during the day because CYA now offers even less protection against sunshine.

However, there is no sunshine overnight. So the only thing that drops FC at night is organics. This has nothing to do with CYA.

 

[Bvacchiano]

So just to be clear if the FC falls overnight regardless of what level it’s at it’s due to organics and not due to just falling back to correct slam level.

 

[ajw22]

So just to be clear if the FC falls overnight regardless of what level it’s at it’s due to organics and not due to just falling back to correct slam level.

Correct!

 

[Hootz]

So just to be clear if the FC falls overnight regardless of what level it’s at it’s due to organics and not due to just falling back to correct slam level.

Cya does not directly affect consumption of fc.....think of it as a sunblock...as if it were forming a layer on the surface to slow the burning off of fc due to the sun.