pH rising faster?

[efm1972]

Split by moderator from HERE. Please start your own thread for your own questions. Thanks, jblizzle.

I read through this string and have the same question. This is 2nd season with pool (pool was finished May 2012). In the first part of this summer, I really did not have the issue of pH going up so rapidly. It did go up, but I was only adding about 1/4 gallon Muriatic Acid about once a week. Not sure what changed (pool filter on the same 10 hours/day and we do not run our fountain, etc.), but I am now adding 1/4 gallon Muriatic Acid about every 2 - 3 days now. Any ideas? Here are my test results:

FC = 5.2
TC = 5.2
pH = 7.9
TA = 90
CH = 260
CYA = 40

Thanks

 

[JasonLion]

If your TA went up, that could account for the difference. Lower TA levels will have less PH drift.

 

[jblizzle]

Maybe the top off water is also at a higher pH and TA than before?

 

[Richard320]

Any chance you got the "safe" fumeless acid, which is half-strength?

 

[jblizzle]

Any chance you got the "safe" fumeless acid, which is half-strength?

This could be a VERY valid explanation.

 

[efm1972]

Thanks for all the responses to my question. I did check my Muriatic Acid, which I purchase from Home Depot and I can confirm that it is not fumeless. Also, when I fill my test bottle, I do so from the same spot in the pool and from the same depth each time. After looking at my test log (yeah, I keep a spreadsheet of all my pool water tests), it is most likely due to a rise in Alkalinity. For the first part of this season, I had kept my TA in the 80 - 90 range. For some reason, I added enough Baking Soda to take TA to 110. Now that it is back down around 90, I am not adding Muriatic Acid as frequently.

Thanks again.