High pH

[jkassner]

Pool was shocked last night--got 1.5 inches of rain overnight. Tested this morning with my new Taylor 2006 kit and results are:
FC: 8.5
CC: 1.5
pH:8.0
CYA: 68 (We are trying to get this at a higher level to use SWG)
TA: 120

Should I do anything about the pH or wait a bit until it comes down? Even with the high FC reading, there seemed to be a little green algae this morning.

Inground vinyl liner pool, 32,000 gallons.

Thanks for any advice.

 

[JasonLion]

If you are already using the SWG and have a TA of 120, it is likely that your PH will continue rising, so I would bring the PH down to 7.2.

If you are currently using trichlor, then leave the PH alone and it will come down on it's own.

 

[jkassner]

The SWG is not in use yet as we are trying to get the water balanced before we put the salt in. The only chlorine I have used is bleach--nothing else. I'll check the water tomorrow and if pH is still high, guess I'll have to use muriatic acid to bring it down. Would your advice still be the same?

 

[Guest]

First a question, how did you get a CYA of 68? The test does not have that kind of precision!
I would work on getting the TA down, that will also get the pH in line. Shoot for 70-80 ppm, that will work for either bleach or a SWG but BEFORE I worry about that I would shock to get rid of the algae. Don't worry about the high pH when killing algae, it can actually work to your advantage by helping monochloramine to form. (It's a very effective algae killer.)

 

[JCJR]

First a question, how did you get a CYA of 68? The test does not have that kind of precision!
I would work on getting the TA down, that will also get the pH in line. Shoot for 70-80 ppm, that will work for either bleach or a SWG but BEFORE I worry about that I would shock to get rid of the algae. Don't worry about the high pH when killing algae, it can actually work to your advantage by helping monochloramine to form. (It's a very effective algae killer.)

Waterbear,

I thought bringing down PH helped CL fight algae quicker?

 

[The Mermaid Queen]

JCJR,

not waterbear, but the lower pH recommendation is for unstabilized pools, or specifically Baqua conversions where you are adding a lot of bleach in a short period of time, which tends to raise the pH. (There is more to it than just this, but I don't know all the specifics!)
In any case, if the OP lowers his TA, that will lower the pH also.

 

[JasonLion]

Also not Waterbear

Many sources say that low PH helps fight algae, and there is a slight bit of truth behind that, but in practice it isn't true. When you don't have any CYA at all, lower PH values do help to some extent. But with CYA the effect mostly disappears. There is much more detail about this here.

Also, there are secondary reactions, involving for example mono-chloramine, that kill algae more effectively at higher PH values, which balance out the slightly lower effectiveness of the direct reactions. The net effect is that PH anywhere in the normal range (72.-7.8 ), with CYA in the pool, is just about the same at killing algae.

 

[frustratedpoolmom]

Pool was shocked last night--got 1.5 inches of rain overnight. Tested this morning with my new Taylor 2006 kit and results are:
FC: 8.5
CC: 1.5
pH:8.0
CYA: 68 (We are trying to get this at a higher level to use SWG)
TA: 120

Should I do anything about the pH or wait a bit until it comes down? Even with the high FC reading, there seemed to be a little green algae this morning.

Inground vinyl liner pool, 32,000 gallons.

Thanks for any advice.

Ditto Waterbear's advice; with a CC of 1.5 you definitely need to shock....