CYA vs. CSI

[CHtoUS]

So my pool seems relatively well balanced, finally. My biggest question mark is around the CYA level. Right now it's at 30 and has been for some time. I raised it to around 45 for a while and it has now dropped again (I assume rain and some dilution to reduce salt).

In the Pool Math app, my CSI value right now shows -0.04, which seems "acceptable" to the app. Long story short, if my CYA were to go to TFP's min. recommendation of 60, my CSI would drop to -0.12, which I think is still ok. But just wondering if that's a trade off that I should make?

My other values, in case it matters:
pH 7.8
TA 70
CH 400
CYA 30
Temp 72
Salt 4200 (I know it's still too high. My Taylor kit shows 3800 but the cell itself shows 4200. I assume it's somewhere in between)

Many thanks for indulging me. I'm a bit confused by these numbers, particularly the CSI.

Roman

 

[ajw22]

Any CSI between +0.6 and -0.6 is ok. Between +0.3 and -0.3 is equally ideal.

-0.12 is as good as -0.04.

Don't try and micromanage your CSI. Just keep it within the goal posts.

Salt 4200 (I know it's still too high. My Taylor kit shows 3800 but the cell itself shows 4200. I assume it's somewhere in between)

Trust the Taylor test and use 3800 for PoolMath. The Taylor test is accurate and the cell reading is a guesstimate.

 

[Texas Splash]

So my pool seems relatively well balanced

Very much so. You're working on slowly increasing the CYA for summer which is a good thing. The heat is coming. You might consider adding your SWG to your signature.

I raised it to around 45 for a while and it has now dropped again (I assume rain and some dilution to reduce salt).

CYA doesn't just fall quickly or dilute, although it does slowly degrade each month anywhere from 5-10 ppm depending on the pool's overall chemistry and other factors. There's also a 10-15% testing variance, so that can account for some CYA number differences.

Overall though, looking good. Keep your numbers within the TFP recommended ranges and all should be well.

 

[CHtoUS]

Any CSI between +0.6 and -0.6 is ok. Between +0.3 and -0.3 is equally ideal.

-0.12 is as good as -0.04.

Don't try and micromanage your CSI. Just keep it within the goal posts.



Trust the Taylor test and use 3800 for PoolMath. The Taylor test is accurate and the cell reading is a guesstimate.

Thanks so much! I really appreciate it.

 

[CHtoUS]

Very much so. You're working on slowly increasing the CYA for summer which is a good thing. The heat is coming. You might consider adding your SWG to your signature.


CYA doesn't just fall quickly or dilute, although it does slowly degrade each month anywhere from 5-10 ppm depending on the pool's overall chemistry and other factors. There's also a 10-15% testing variance, so that can account for some CYA number differences.

Overall though, looking good. Keep your numbers within the TFP recommended ranges and all should be well.

Makes sense, thank you for taking the time to reply!

 

[xDom]

Any CSI between +0.6 and -0.6 is ok. Between +0.3 and -0.3 is equally ideal.

This is interesting, didn't realise there was this much tolerance in it.

 

[ajw22]

This is interesting, didn't realise there was this much tolerance in it.

And any bad things from being out of CSI range take weeks if not months to develop.

Don't go chasing say to day deviations of CSI outside the good range as long as it comes back into range within a few weeks.

 

[xDom]

And any bad things from being out of CSI range take weeks if not months to develop.

Don't go chasing say to day deviations of CSI outside the good range as long as it comes back into range within a few weeks.

I have a fibreglass pool, I only have solar matt heating on my roof as well. So really, there's not much damage that could occur even if I am out on my LSI?

 

[ajw22]

I have a fibreglass pool, I only have solar matt heating on my roof as well. So really, there's not much damage that could occur even if I am out on my LSI?

With a FG pool and no waterline tile with grout CSI is really not applicable.

Nothing bad can happen to you with low CSI.

Extended periods of high pH causing high CSI can form scale on your pool. That is easier to remove on a FG pool with acid then other surfaces.

CSI is not something we tell people with FG pools to track and why it is an option in
PoolMath