PH rising every few days, everything else ok, how to fix?

[Ejosh87]

So I started taking care of the pool myself finally about 1-2 months ago. Everything has been smooth and going great but the PH keeps raising it seems no matter what I do. I've been adding muriatic acid to bring it back down but usually within 4-7 days it's back to 8.0-8.2. The rest of the levels I believe are good, and the water looks great. I have a spa that overflows to the pool so I tried lowering the settings on my SuperFlo VS to make it so the overflow is very little:

1700 - 1 hour (overflow slightly more than trickle)
1100 - 4 hours (overflow trickles, almost not noticeable at all)
1700 - 1 hour (overflow slightly more than trickle)

The pool levels are below:

FC - 9
TA - 90
CYA - 60
CH - 275
PH - 8.1 (currently but just added muriatic acid again)


Any suggestions on how to resolve this? Maybe I need to lower the TA? If so, what would be the best way to do that while keeping everything else optimal?

Thanks

 

[IceShadow]

Has the TA been coming down over time as you've been adding the acid? That's usually what happens. When it gets up to the 8.0+ level you can add to get back down to 7.4 - 7.6 and the TA will drop over time. This will also lower your need to add acid.

I do see you have a plaster pool - has the plaster been redone recently at all?

 

[Jimrahbe]

Josh,

Keep in mind that your spa spillover is what keeps your spa chlorinated.. I suggest that you test the spa water every now and again to make sure your "trickle" is supplying enough fresh water to keep the spa chlorinated.

Your pH issue sounds about right to me.. Adding acid every 4 to 7 days is not all that unusual.

Thanks,

Jim R.

 

[Ejosh87]

The TA has been coming down very slightly, maybe from 100 to 90 over 1-2 months.

As for the spa spillover, that's one thing I'm still slightly confused about, I read some threads where it seemed having it spillover for 6 hours even on trickle is too much since that raises PH, and others where it seemed to say the opposite. For testing, should I do all the tests on the spa water (TA, CH, FC, CYA, etc?) and if they are same as the pool then it is fine? If they are not same, then I would either have to adjust the returns so instead of 75/25 (pool/spa) it would be 50/50? and/or raise the RPM on the pump?

Thanks for the advice

 

[Jimrahbe]

Josh,

You only need to compare the FC of the pool with the FC of the spa.. They should be "about" the same. If not, you will need to run the spillover longer or harder..whatever works for you.

Jim R.

 

[Ejosh87]

Josh,

Keep in mind that your spa spillover is what keeps your spa chlorinated.. I suggest that you test the spa water every now and again to make sure your "trickle" is supplying enough fresh water to keep the spa chlorinated.

Your pH issue sounds about right to me.. Adding acid every 4 to 7 days is not all that unusual.

Thanks,

Jim R.

So I ran the test to compare SPA and POOL and both showed FC of 9. Assuming that would be a good indicator that the trickle is sufficiently mixing the water and can leave as-is?

 

[Jimrahbe]

Sounds like a plan to me...

Jim R.