Ph vs CSI

[DerrikM]

With 50 borates, the 24 oz of MA you added would not lower your pH by 0.1 units.

You need to use Poolmath to determine acid volumes needed to lower pH. Do not lower by more than 0.4 units at a time.

By my calculations, you need 1 gallon of 31.45% MA to lower the pH by 0.4 units. Check those figure

So, rather than trying to calculate my pH, knowing that it is definately over 8, should I just go ahead in add 1 gallon of acid at a time until I get a reading in the 7.6 range? How long do I need to wait before testing and adding more acid? Also, according to Poolmath 1 gallon of acid will lower my TA by 50. How do I deal with that as my TA is fairly steady at 70 to 80?

 

[mgtfp]

Just to rephrase what Marty already said: The Acid Demand Test test table in the Taylor booklet doesn't consider Borates. And Poolmath probably also gets to its limits that far away from typical pool pH.

(Edit: actually, the acid demand test doesn't really bother about the borates, it's just a scaling from mini-pool to a maxi-pool.)

Assume that your pH is 8.2 and calculate with Poolmath how much acid to add to get down to 7.8 (as Marty said, don't aim for more than 0.4 reduction). Add acid, test after 30 min with pump running. Repeat until you get to 7.8-8.0. Retest TA in-between as well, as that will decrease with every acid addition and affect the required acid amounts. If your pH really is at 8.8 (Edit: I don't think your pH is that high, just want to point out what can happen in a scenario like that), then taking it down to 7.8 would reduce your TA from 80 down to nearly 30. Don't take TA below 50. Once TA is that low, I'd expect pH to drop further down on it's own by CO2 absorption from the atmosphere. Is your pool open or covered?

 

[DerrikM]

Just to rephrase what Marty already said: The Acid Demand Test test table in the Taylor booklet doesn't consider Borates. And Poolmath probably also gets to its limits that far away from typical pool pH.

(Edit: actually, the acid demand test doesn't really bother about the borates, it's just a scaling from mini-pool to a maxi-pool.)

Assume that your pH is 8.2 and calculate with Poolmath how much acid to add to get down to 7.8 (as Marty said, don't aim for more than 0.4 reduction). Add acid, test after 30 min with pump running. Repeat until you get to 7.8-8.0. Retest TA in-between as well, as that will decrease with every acid addition and affect the required acid amounts. If your pH really is at 8.8 (Edit: I don't think your pH is that high, just want to point out what can happen in a scenario like that), then taking it down to 7.8 would reduce your TA from 80 down to nearly 30. Don't take TA below 50. Once TA is that low, I'd expect pH to drop further down on it's own by CO2 absorption from the atmosphere. Is your pool open or covered?

Pool is not covered. Thanks for all of that clarifcation. Now I have a straight forward and logical plan. I'll be dealing with tons of leaves ad then pollin in March/early April, and will do a partial drain/refill based on fill water chemistry. Looking to get everything back to normal again. I can always depend onthe advice given here. I am sure that a pool store would be selling me lots of products, all of which would pit me in a never ending cycle of ups and downs.

 

[Texas Splash]

I'll be dealing with tons of leaves ad then pollin in March/early April

Be sure to have a skimmer sock installed. It helps tremendously.

 

[DerrikM]

Be sure to have a skimmer sock installed. It helps tremendously.

Will do. I use them every Spring.

 

[DerrikM]

With 50 borates, the 24 oz of MA you added would not lower your pH by 0.1 units.

You need to use Poolmath to determine acid volumes needed to lower pH. Do not lower by more than 0.4 units at a time.

By my calculations, you need 1 gallon of 31.45% MA to lower the pH by 0.4 units. Check those figures yourself.

According to my poolmath app an addition of 1 Gal of 31.35 acid to my 10,000 gallon pool would reduce pH by 3.1 and TA by 50.0.
Today my results were pH approx 8.4 and TA 80. I added 16 oz acid and an hour later pH was 7.8 and TA 80. I then added another 16 oz of acid and an hour later results were pH 7.4 and TA 80. I am happy with pH but have no idea why TA never moved off of 80.

 

[mknauss]

With those results, you do not have 50 ppm borates.

 

[DerrikM]

With 50 borates, the 24 oz of MA you added would not lower your pH by 0.1 units.

You need to use Poolmath to determine acid volumes needed to lower pH. Do not lower by more than 0.4 units at a time.

By my calculations, you need 1 gallon of 31.45% MA to lower the pH by 0.4 units. Check those figures yourself.

According to my PoolMath app adding 1 Gal 31.45 acid to my 10,000 gal pool would lower pH by 3.1 units and TA by 50.0.
Today I checked levels for pH and TA and they were pH 8.4 (approx) and TA 80. I added 16 oz acid, waited and hour with pump at high speed and pH dropped to 7.8 and TA stayed at 80. Added another 16 oz acid and waited another hour, pH dropped to 7.4 and TA again stayed at 80. I did add a little bit, about 1 inch of fill water while doing this and that might account for the TA. I tested my fill water today and TA is 140.

 

[DerrikM]

With those results, you do not have 50 ppm borates.

I tested twice with LaMotte test strips, both indicated 50

 

[mknauss]

Not chemically possible to get that pH change, with that amount of MA, with 50 ppm borates. The strips are not correct.

 

[DerrikM]

Not chemically possible to get that pH change, with that amount of MA, with 50 ppm borates. The strips are not correct.

I thought that PoolMath adjusted for the Borates. If so, how come my PoolMath Effects of Adding shows me that 16 oz of acid will give me a pH reduction of 0.4. I am not questioning your chemistry as I have very chemistry knowledge other that what I learn here and from using PoolMath. But, how did you arrive at the 1 gallon number? By the way, I will order new test strips even though these havent expired. And in the same vein, I will probably not add additional Borates after doing 1/2 drain and refill in the spring.

 

[mknauss]

The Effects of Adding does not use all the parameters and is an estimation. You must use the calculation based from your data logs.

 

[mgtfp]

16oz should reduce TA by about 6-7 ppm, so might just not be detectable with the test. But adding 16oz twice should be visible in the TA-test. Maybe is wasn't full strength acid?