SecoSteve

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Jul 28, 2020
225
Lincoln University, Pa
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25000
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Plaster
Chlorine
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Jandy Aquapure 1400
During our first season, the TA was always above 60(60-100). When I opened this spring, it was hovering between 60-70. I've been dosing with Muriatic acid to keep Ph in check, and that addition has steadily been lowering TA. I'm now sitting at TA 50, and I feel I'm approaching TA 40. When I do the drop test, I see that 4th drop nearly changing pink, but not quite. The 5th drop definitely changes.

My question is.... Do I add what Pool Math says, and add around 7lbs of baking soda to bring TA up to 70? If so, can I mix it in a bucket and broadcast into the pool?
 

duraleigh

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Yes, I think you should add the 7 lbs. It dissolves quite readily and the few times I have added baking soda, I have simply broadcast it across the pool or (pump running) you could just pour it slowly into the skimmer. It is an easy product to work with so no real need to pre-dissolve
 
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JoyfulNoise

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May 23, 2015
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It sounds like your adding too much acid and chasing a specific pH. If you keep doing that, you lower TA in the process and then you add baking soda to raise TA completely undoing all the acid additions. You’re going to find yourself in yo-yo situation soon. Perhaps you can post a full set of water test results and also post test results for your fill water.
 

SecoSteve

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Jul 28, 2020
225
Lincoln University, Pa
Pool Size
25000
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Plaster
Chlorine
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Jandy Aquapure 1400
It sounds like your adding too much acid and chasing a specific pH. If you keep doing that, you lower TA in the process and then you add baking soda to raise TA completely undoing all the acid additions. You’re going to find yourself in yo-yo situation soon. Perhaps you can post a full set of water test results and also post test results for your fill water.
Hi Matt

The acid additions are necessary to keep Ph in the 7's. New plaster pool in 2020. My Ph is always trending into the 8's, even after bringing it down to the 7's. I would love to NOT have to add MA. Any recommendations?
 

Sunnydaze

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Mar 8, 2021
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Hi Matt

The acid additions are necessary to keep Ph in the 7's. New plaster pool in 2020. My Ph is always trending into the 8's, even after bringing it down to the 7's. I would love to NOT have to add MA. Any recommendations?

What is your target ph when you add acid?
 

Rancho Cost-a-Lotta

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When I do the drop test, I see that 4th drop nearly changing pink, but not quite. The 5th drop definitely changes.
Steve,

Did you try a 6th drop? I can sometimes get 2 or 3 shades of red before the color change stops. When doing the TA test, keep dropping until there's no further color change. Don't count the last drop that results in no change.
 

SecoSteve

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Jul 28, 2020
225
Lincoln University, Pa
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Steve,

Did you try a 6th drop? I can sometimes get 2 or 3 shades of red before the color change stops. When doing the TA test, keep dropping until there's no further color change. Don't count the last drop that results in no change.
The fifth drop definitely changes to pink, but I can tell on the fourth drop that it's coming up next drop.
 

JoyfulNoise

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May 23, 2015
20,704
Tucson, AZ
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Pentair Intellichlor IC-60
It would be helpful if you linked your PoolMath App to your forum profile so that we see your testing data or you can just post your latest test results. Also need to know what your fill water test data is (pH,TA and CH).

A pool completed in 2020 should not be having as much acid demand. Everyone likes to state that it takes years for plaster to "settle down" but that is simply not true. So there is something else driving your pH and it could likely be your fill water. Also, are there any sources of aeration in pool like waterfalls, bubblers, spa, etc?

In any event, just because the App defaults to 7.2 doesn't mean you have to accept that. You can change the target pH to whatever you like. In your case, you really shouldn't be dropping your pH below 7.6 and then you should only add acid once it gets above 7.8/7.9. When you do that, your TA will likely stabilize and acid additions should start to stretch out more. Again, this depends a lot on what sources of alkalinity are being added to the pool or if outgassing of CO2 is bering driven by external factors.
 
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SecoSteve

Silver Supporter
Jul 28, 2020
225
Lincoln University, Pa
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
It would be helpful if you linked your PoolMath App to your forum profile so that we see your testing data or you can just post your latest test results. Also need to know what your fill water test data is (pH,TA and CH).

A pool completed in 2020 should not be having as much acid demand. Everyone likes to state that it takes years for plaster to "settle down" but that is simply not true. So there is something else driving your pH and it could likely be your fill water. Also, are there any sources of aeration in pool like waterfalls, bubblers, spa, etc?

In any event, just because the App defaults to 7.2 doesn't mean you have to accept that. You can change the target pH to whatever you like. In your case, you really shouldn't be dropping your pH below 7.6 and then you should only add acid once it gets above 7.8/7.9. When you do that, your TA will likely stabilize and acid additions should start to stretch out more. Again, this depends a lot on what sources of alkalinity are being added to the pool or if outgassing of CO2 is bering driven by external factors.
My logs should be visible. Let me know if not. We have two bubblers on our ledge, but only use them sparingly. Also, they don’t “bubble” as much as we thought they would. The ledge has 12” of water and there are no restrictors on the output of the bubblers. We do have a SWG.

Fill water test:

Ph 7-7.2
TA. 80
CH 25(all water spigots from softener)
 

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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
20,704
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
My logs should be visible. Let me know if not. We have two bubblers on our ledge, but only use them sparingly. Also, they don’t “bubble” as much as we thought they would. The ledge has 12” of water and there are no restrictors on the output of the bubblers. We do have a SWG.

Fill water test:

Ph 7-7.2
TA. 80
CH 25(all water spigots from softener)

Your TA isn't bad but the low pH combined with high'ish TA will cause the outgassing of CO2 and the eventual rise in pH. I suggest you continue to restrict the use of any aeration sources and target a pH of no lower than 7.6. When it rises up to 8.0, knock it back down to 7.6. If you do that, I believe your TA will stabilize to around 70ppm. Your fill water TA will drive your pH rise as you are naturally adding bicarbonate anions to the water.

You could also try adding borates to the water. That may help to hold down the rate at which the pH rises and give you more time between acid additions.
 

SecoSteve

Silver Supporter
Jul 28, 2020
225
Lincoln University, Pa
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
So I drove up TA to 80 last night and confirmed that with today’s test. Ph tested at 8.2 again. I dosed with MA to bring it down to 7.6. I’m concerned that the Ph is actually higher than 8.2, as the test looks red. Other than aeration, which I think is low for this pool, as we don’t use the bubblers much, the only other thing I see affecting Ph is the SWG. I keep returns from breaking the surface. Fill water test above can’t be the reason either. Don’t know what else to do except keep dosing with MA.