pH and Alkalinity Advice

[bobazonski]

Hi everyone, I have done extensive research on this topic but I think I need a little help putting together a plan of attack when it comes to addressing the pH balance in my pool.

Background:
I took over maintaining my own pool and recently, and also drained and refilled the water. After filling, the TA started off ~145, so I have slowly brought it down to ~90 using muriatic acid while simultaneously battling high pH. My pool has a spillover which may be contributing to the continual rise in pH, and my TA also has a tendency to rise on its own.

The issue:
My pH drifts upward rather quickly, as shown by the following:
Test results from 5/10 (~1 day after adding MA with the pump on):
pH: 7.4
TA: 90
Test results from today, 5/13:
pH: 8.0
TA: 90

My goal is to keep LSI in check and prevent scaling, but with these numbers, I'm needing to add acid every 2-3 days to avoid going well over LSI of 0.3.

What do you recommend? Should I bring the TA down lower, or am I risking even faster swinging of the pH? Should I try the borates technique?

Any assistance is appreciated.

Here are all of my current test results/pool info in case it matters:
FC: 2.4 | CC: 0.2 | pH: 8.0 | TA: 90 | CH: 360 | CYA: 25 | Salt: 0 | TDS: 600 | Water temp: 80F | Pool volume: 10,000 gal

 

[Texas Splash]

Bob, a few things to help you get a handle on this issue:
- First, how are you testing? Hopefully you are using your own TF-100 or Taylor K-2006C test kit. Please add that kit and your pool info to your signature. The TDS number makes me think you are still using a pool store for testing. Booooo!
- Is this new plaster? If yet, it's still curing and pH will rise quicker. If no, then no big deal.
- You can still lower the TA a bit more which should help to slow the rise of pH. To do that, let the pH rise to 8.0 then lower it with enough acid to go down to 7.0. That wider range of drop will have more impact on the TA. I would allow the TA to go down to 70 and see how that works.
- Yes, limit any forms of aeration (i.e. spillovers). Run only when absolutely necessary or to purge water in a spa
- Your CYA and FC is a bit low after the refill. This time of year in the Vegas Valley, you want a CYA of at least 40, maybe even 50. Jun - Sep probably 60-70. But as you increase the CYA, be sure to increase the FC with it as noted on the FC/CYA Levels . Your FC is a bit low right now.

Give that a look and let us know if you have any questions.

 

[bobazonski]

Thanks for the response! I am testing using a Taylor K-2006C with all new reagents. (I learned about the issues with pool store testing when I saw firsthand how much the results vary after visiting only about a week apart ) I do still go to the pool store every month or two to confirm my own results and also get the TDS level. The plaster is old so I don't think it's playing a role here. As for the CYA and FC, since I refilled recently, I'm still working on raising the CYA by using tablets I already had on hand, with the intent to switch to liquid chlorine once CYA gets to ~50. With the CYA so low, the FC swings back and forth a bit and happened to be a little low when I took that test.

Thanks for recommending 70 for the TA. I'll get it there and see how that goes!