Ph and CSI

[TeenaTeens]

I have been away two weeks and using water guru to test for FC and Ph each morning. These two readings are accurate in the new Sense 2 model. I want to know if I need to get my wife to add MA to lower the Ph which has risen to 8.2. And if so what do I lower it to? My CSI is great as it is and if I lower the Ph the CSI goes out. Just a bit confused running my TA lower than I was after getting flakes. Any advice would he gratefully received. I get home Wednesday.

 

[PoolStored]

Lower it to 7.6. You should be good.

 

[TeenaTeens]

Lower it to 7.6. You should be good.

That increases my CSI to -4… so that’s ok?

 

[Bperry]

That increases my CSI to -4… so that’s ok?

-4 would be bad but -.4 is ok.

 

[JamesW]

I would probably leave it alone or maybe only drop it to 8.0.

 

[TeenaTeens]

-4 would be bad but -.4 is ok.

I would probably leave it alone or maybe only drop it to 8.0.

Interesting. No matter what I do it always raises to around 8. And then it sits like that. I’m tempted to just leave it. 8.1. 8.0. 8.2. I just wasn’t sure if that was ok. Just leave it. I read all about the Ph ceiling. My csi is perfect with it at this number.

 

[PoolStored]

It is very possible that your newer pool plaster is still causing pH to rise. It is not unheard of for pH to rise through 18-24 months after installation. There are even a few that still get pH rise into 3 years, but is rare.

 

[JamesW]

Interesting. No matter what I do it always raises to around 8. And then it sits like that. I’m tempted to just leave it. 8.1. 8.0. 8.2. I just wasn’t sure if that was ok. Just leave it. I read all about the Ph ceiling. My csi is perfect with it at this number.

Note that it is only my opinion that it is ok to leave the pH at 8.0 or 8.2.

Your builder might not agree and the plaster company might not agree.

If there is an issue with the plaster and you are not keeping the pH in a range that they think is good, they might blame the pH for any future problems.

They are not going to care what I think.

They are not going to say "Oh, some random person on the internet told you that it was ok to let the pH sit at 8.2? Well, that's good enough for us".

So, you have to decide what to do based on your own opinion about what is the best thing to do.

The main issue is controlling the CSI, which depends on the calcium hardness and the carbonate level CO₃^2-.

The carbonate level depends on the amount of carbonate alkalinity and the pH.

The builder and the plaster people probably do not understand the full chemistry involved, so they just use simple "Rule of thumb" to figure out what the numbers should be.

In any case, you should be aware of the numbers that the builder recommends and the numbers that the plaster company recommends.

If you decide to go outside of their recommended ranges, you do it at your own choice and your own risk.