PH rise and acid additions....

Oscar G.

Well-known member
Hello, I would like to get your thoughts on the frequency of MA additions to my pool. We opened the pool last July and I feel like the PH is rising pretty fast after each addition of MA. I have been adding acid when the PH gets to around 8 and I've been targeting 7.5.

4/12/20 PH was 8 and I added 12 oz 31% ma to bring the PH down to 7.5.
4/13/20 PH was up to 7.8.
4/14/20 Ph was up to 8 (TA 70). I added 12 oz MA targeting 7.5. The TA still read 70ish.

My latest tests of the other levels were as follows: FC 5.5, CH 575, CYA 60, CC .5, salt 3200. Also, my fill water is 7.5 PH .

So, I am adding acid every couple days to keep my PH with the acceptable range. Based on info in other posts, I hoped my PH would be more stable by now. Ive also read that lowering the TA could help buffer PH but I don't know if I should go any lower. Thanks for any advice you could give me! :)
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,261
Laughlin, NV
Manage your CSI. Such that you may want a lower TA (60 or 70) so your pH can remain at 7.8 or 8.

It is pretty normal to have to add acid every few days to a week here in the SW desert. Your fill water TA I suspect is 130+ and thus there will always be an upward pressure on pH.

I assume you have no sources of aeration, such as bubblers, fountains, waterfalls, running on a regular basis.
 

Oscar G.

Well-known member
Manage your CSI. Such that you may want a lower TA (60 or 70) so your pH can remain at 7.8 or 8.

It is pretty normal to have to add acid every few days to a week here in the SW desert. Your fill water TA I suspect is 130+ and thus there will always be an upward pressure on pH.

I assume you have no sources of aeration, such as bubblers, fountains, waterfalls, running on a regular basis.
I will test my fill water but I have no water features.
 

Oscar G.

Well-known member
Manage your CSI. Such that you may want a lower TA (60 or 70) so your pH can remain at 7.8 or 8.

It is pretty normal to have to add acid every few days to a week here in the SW desert. Your fill water TA I suspect is 130+ and thus there will always be an upward pressure on pH.

I assume you have no sources of aeration, such as bubblers, fountains, waterfalls, running on a regular basis.
Fill water is 120 TA
 

DanF

Silver Supporter
Mar 17, 2019
127
Chandler, AZ
It is pretty normal to have to add acid every few days to a week here in the SW desert. Your fill water TA I suspect is 130+ and thus there will always be an upward pressure on pH.
Is this true Marty? I ask because I have been trying to get my pH down from 7.8 for a couple of weeks now. When add two drops of Acid Demand reagent from my K-2006C, the comparator shows 7.6. But when I add the necessary muriatic acid from the table for 2 drops (23 oz), I see no change in color. I have done this process 2 or 3 times now and am afraid to add more. When testing pH I add only 4 drops of the red phenol solution as you recommended.

My TA is a little high at 95-110, but I suspect that is normal for the area in which I live. One other note is that the MA I am using is 29%, not 31%, but would that make much of a difference?

Thanks
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,261
Laughlin, NV
You will add acid here as your fill water TA will push it up. I find if I drop my pH from 7.6 or 7.8 to 7.4 or so twice a week, I can keep my TA at 70 ppm or so. During the summer. Right now I do not have much issue as I cover the pool at night to keep it warm and thus evaporation is fairly low.

I do not use the acid demand thing. I use Poolmath.

The 29% MA will work fine. You just have to use a bit more than what Poolmath tells you for 31.45%. Does not Home Depot have the 31.45% MA in your area?
 
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DanF

Silver Supporter
Mar 17, 2019
127
Chandler, AZ
Thanks Marty. I'll keep adding acid and see what happens, and try Poolmath also. I guess my current pH could be above 8.0 but the color doesn't look red enough to me.

My pool is definitely warming up...not sure of the exact temp but yesterday at 4:00 my outdoor thermometer read 106 and 1% humidity! So my autofill is probably kicking in.

Not sure about Home Depot's MA percentage. Last time I looked it was only 15%, so I bought my current 29% case at Leslie's. I'll check again when I need to restock. I did find 10% Pool Essentials chlorine at WM today, only 30 days old! One of the effects of COVID is that our summer vacation plans have pretty much gone kaput, so I won't be using trichlor tabs as much as I had planned.
 

cbaird99

Member
Jul 12, 2019
13
Texas
Is this true Marty? I ask because I have been trying to get my pH down from 7.8 for a couple of weeks now. When add two drops of Acid Demand reagent from my K-2006C, the comparator shows 7.6. But when I add the necessary muriatic acid from the table for 2 drops (23 oz), I see no change in color. I have done this process 2 or 3 times now and am afraid to add more. When testing pH I add only 4 drops of the red phenol solution as you recommended.

My TA is a little high at 95-110, but I suspect that is normal for the area in which I live. One other note is that the MA I am using is 29%, not 31%, but would that make much of a difference?

Thanks
Just reading this as I am having a highish Ph as well...may I ask why you are only using 4 drops of the test solution not 5?
 

cbaird99

Member
Jul 12, 2019
13
Texas
It makes comparing the colors easier for me. The number of drops changes the intensity of the color.
Ah ok thank you! So you will still be able to gauge your PH but it's easier to tell where you are. I am gonna try this as I have trouble with this as well, thanks for the tip! I think I will order one of those test meters too, it seems like a good product to also have.
 
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DanF

Silver Supporter
Mar 17, 2019
127
Chandler, AZ
Even trying to assess pH with 4 drops instead of 5, I still have trouble. Either my pool is really stuck at a pH of 7.8 or I'm not interpreting the results correctly. Let me know which electronic tester you decide on.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,261
Laughlin, NV
I would call that 8.

Test your TA. Use that value to determine how much muriatic acid to use to lower your pH from 8 to 7.6. Add the acid. Let it circulate for 30 minutes to an hour and test the pH again.
 

DanF

Silver Supporter
Mar 17, 2019
127
Chandler, AZ
Ok will do tomorrow. Need to head out for a bit now. I think my TA is 110 from a test last week, from which pool math shows 15 oz of my 29% MA, but I will retest my TA tomorrow first. Thanks Marty!
 
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DanF

Silver Supporter
Mar 17, 2019
127
Chandler, AZ
OK I tested my TA this morning and it came in at 100. So I added 14 oz of 29% MA and tested pH 45 minutes later. Here are the pics, one white background and one in front of a south facing window.
What do you think?
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