PoolMath App - pH calculation isn't correct

[Bamamojo]

Hi everyone, so I have been using the app for Android for maintaining my 17500 gallon, SWG, plaster inground pool. pH calculation on app is incorrect. I tested my water today and pH was 8.3. The app says to just add 3.7 ounces of muriatic acid. Leslies testing tells me to add 57 ounces, and the old TFP calculator tells me to add 38. I am inclined to believe the old calculator. I am a registered user and did log in to the app - just to be clear.
Anyone knows what is going on with the app? I wonder if I am doing something wrong... Thanks in advance!

Marcos (Arlington, TX)

 

[dfwnoob]

Are you confident your pool size in the app isn't 1750 instead of the 17500 it should be?

 

[Bamamojo]

Are you confident your pool size in the app isn't 1750 instead of the 17500 it should be?

Yes I am. Just re-checked. Thank you for reply.

 

[mknauss]

Share your Poolmath data so we can see what the issue is.

 

[Bamamojo]

Hi everyone, so I have been using the app for Android for maintaining my 17500 gallon, SWG, plaster inground pool. pH calculation on app is incorrect. I tested my water today and pH was 8.3. The app says to just add 3.7 ounces of muriatic acid. Leslies testing tells me to add 57 ounces, and the old TFP calculator tells me to add 38. I am inclined to believe the old calculator. I am a registered user and did log in to the app - just to be clear.
Anyone knows what is going on with the app? I wonder if I am doing something wrong... Thanks in advance!

Marcos (Arlington, TX)

Okay, after dfwnoob suggested I verify pool size I went back and also looked at all the entries on the pH page. I was missing total alkalinity. Once I entered that number it gave me the proper result. Issue resolved -Thanks!

 

[Bamamojo]

Share your Poolmath data so we can see what the issue is.

It was operator error, lol. I left the total alkalinity entry blank! Thank you sir.

 

[midlifecrisis]

I guess this is a real world example of how low alkalinity can cause wild swings in PH? I've done a considerable amount of reading on the topic today while learning a little more about containing my own PH.

 

[mknauss]

More that the calculations do not work for wildly variant conditions. With a 0 TA, you would have a pH of 4.5. So the calculations are way out of the range of use.

 

[Bamamojo]

I guess this is a real world example of how low alkalinity can cause wild swings in PH? I've done a considerable amount of reading on the topic today while learning a little more about containing my own PH.

Yes it is! So I am struggling with maintaining proper pH - always on the high side 8.1 - 8.3 if I don't add acid every day. I haven't been really paying too much attention to TA other than when Leslies tester tells me it is out of range. I will pay more attention to this number going forward. Right now it is 77, low end of the range of 80-120. Thanks for sharing

 

[mknauss]

Leslies tester tells me it is out of range.

low end of the range of 80-120

I recommend you get your own proper test kit and follow TFPC. Or, use Leslies and follow their recommendations. Mixing the two does not work and creates confusion for both of us.

 

[ajw22]

Yes it is! So I am struggling with maintaining proper pH - always on the high side 8.1 - 8.3 if I don't add acid every day. I haven't been really paying too much attention to TA other than when Leslies tester tells me it is out of range. I will pay more attention to this number going forward. Right now it is 77, low end of the range of 80-120. Thanks for sharing

Leslie gives you an adjusted alkalinity value.

TFP recommendations are based on using your own test kit.

Your TA from a recommended test kit will likely be higher.

If you want to follow TFPC then get your own test kit and do your own testing.