lowering TA

[Johnny B]

Thursday 6/18/2015
pH7.6 so pH is increasing too much/too fast, about 1.3 ppm/day, so I want to decrease TA to about Target 55 Target by lowering the pH to about 7.2 and then aeration to increase the pH, did a one hour retest and pH was at 7.2
FC 8 so
CC 0
TA 70, decrease TA to Target 55 via 29 oz acid to Target pH7.2 then aerate until pH gets to ph7.5
CH 225, Target 250 with 59oz oz by volume of calcium chloride
CYA 30-40 assume 30 Target 45 with by weight or 41oz by volume ; very little rain so frequent tap water addition of about 0.75 inches every 3 days
borates 0
85° F
CSI: balanced only if ph is7.4-7.9 & ^ the CH did not help keep CSI balanced

Saturday 6/20/2015
pH equal 7.5 or 7.6, so aeration got pH back in range in about 36 hours
TA 70, I was hoping it would be lower. The evening of 6/19/20 we got about 1.25 inches of rain, unsure if that is an issue. Also unsure if the additions for CH & CYA had any impact which are no longer indicated today.

I want to lower my TA. The past 2-3 summers by getting TA in the 50 range there was much less frequent addition of acid, Jason ok'd it (TA50 does not work for me in the winter, only the summer).
My question is: just want me to hit it again with the acid + aeration? You want me to target pH 7.0 instead of pH7.2?

All questions and comments appreciated

 

[tim5055]

Acid + aeration and you will get there.

 

[pooldv]

Here is the process for Lowering Total Alkalinity

Also, adding borates can help stabilize TA. More here, Borates - Why and How

 

[Johnny B]

Thanks to everyone.
But I think I'll quit, went thru this 3 times & TA hasn't budged.
Would it make any difference if I went to pH 7.0 instead of 7.2?

 

[pooldv]

You can try going to 7.0. Are you aerating back up to 7.8 or 8? That can help. The TA drops only measure 10ppm per drop. So, 3 times might not be enough to move it to the next 10.

 

[DanielP]

From what I recall reading, aeration wiil increase pH faster when the pH is lower, so you can go from 7 to 7.2 faster than 7.2 to 7.4. 1.3 ppm pH swing seems pretty high, are you getting bubbles coming out of your return jets or have a large fountain? I'd definitely consider borates to buffer the pH rise.

 

[Johnny B]

August 2016 update: I had to revisit this thread because I need to do this again, just the conditions of my pool I suppose. Hoping to help others who might have this issue of "pool is requiring too much acid".
I failed to post last year that after I wrote " I quit after 3 attempts", that I re-tested TA 6 days after the final attempt & my TA was TA 60 so good news to me; and that the acid demand was more reasonable which was the whole reason for doing it. My acid demand seems to be most reasonable around a TA of 50-55 but TA 60 was just fine so I left it at that
Also based on my experience, and what someone posted above:
- I am going to target pH 7.0 instead of pH 7.2 (pool calculator indicates if you want to lower TA you can target pH 7.0-7.2).
-I'm going to aerate until my pH is in the pH 7.8 range (pretty sure last year that I only went to pH 7.5); then I'm going to lower pH to pH 7.5; then I'm going to wait 6 days before retesting TA, and then hit it again with acid if I'm not happy because the TA is not in the 50-60 range.

FWIW, I did have borates in the pool during the years PRIOR to this "too much acid required" problem. I liked the borates, just to lazy to do it again so maybe this will inspire me to do it next season?