Adjustment Recommendations (high TA, low pH)

[McAlsop]

I am using the PoolMath app, but I can't tell what to do as the recommendations for TA and pH are opposite.

For alkalinity, my test kit measured 150ppm, and using the formula (pH=7.3; CYA=80) I get carbonate alkalinity is 126.8. [Should I be using this as my reported alkalinity in the app?]

The problem is that the recommended (ideal) alkalinity is 50-90 (60-80), so I'm at least 40ppm higher than recommended.
However, my pH is at 7.3 (crept up from 7.1 over the last week), which is within the recommended range (7.2-8.0) but not ideal (7.6-7.8).

For lowering the alkalinity, the app suggests I "reduce pH to 7.0-7.2 with acid and then aerate to increase pH"
But it also suggests raising the pH by using washing soda/borax (20 mule).

What should I do? Thanks in advance!

All measurements: (FC=6.5; CC=0.5; pH=7.3; TA=127; CH=425; CYA=80; SALT=3,790; TEMP=84f; CSI=-0.15)

 

[mknauss]

Welcome to the forum!
TA is the parameter to be least concerned about. Enter your tested TA into Poolmath. No adjustments are needed.
Your CSI can go as high as 0.0, so it would be wise to lower the TA over time so you do not need to keep your pH low.
You raise the pH with aeration, not chemically.
Read Lower Total Alkalinity - Trouble Free Pool
I suggest you read ABC's of Pool Water Chemistry.

 

[Saturn94]

IMHO, your numbers are fine and your pH isn’t rising rapidly, so no action necessary. As you’ve noticed, your pH will creep up on it‘s own.

Chasing “ideal” numbers will just drive you crazy.

 

[Richard320]

Go swimming.

If your readings are in the acceptable range, accept them! If they're not, you need to adjust them, so you need to pick a target. You might as well pick one that's ideal, rather than just acceptable. That's the difference between acceptable and ideal. Chasing ideal numbers that will move with water additions and swimmers is an exercise in futility. It is good for driving sales in the pool store, though.

 

[kevinskii]

Also, consider testing your tap water for reference. This will give you a sense of whether chasing "ideal" numbers is worthwhile. Mine has TA=90-100 and pH>>8, so I know I'll just have to live with adding a cup of acid every day or so.

 

[McAlsop]

Wow, after all my searching, I never saw that specific article about lowering total alkalinity. Thanks! I am almost always aerating, so I'll just let the pH increase; it was 7.1 last week and 7.2 over the weekend, so it's going...

 

[kevinskii]

Lucky you! My pH increases by about 0.1/day.

 

[McAlsop]

Also, consider testing your tap water for reference. This will give you a sense of whether chasing "ideal" numbers is worthwhile. Mine has TA=90-100 and pH>>8, so I know I'll just have to live with adding a cup of acid every day or so.

So we have a hot tub, which I refill every 3-4 months and the initial sample always tells me what the current tap chemistry is. My most recent fill was last week, and the tap pH was 7.6, TA was 220, and CH was 400.

I guess I didn't really know what the "acceptable" range is for alkalinity - just recommended and ideal ranges - and I was 40ppm above the highest recommended amount.

In any case, I'm glad I asked instead of tinkering more!

Appreciate your help and friendliness!