Total alkalinity question


Aug 18, 2015
Is there any reason I need to keep my total all between 125-150? This is higher than what my caldera manual tells me it needs to be. Caldera says keep it at a minimum of 40. The people at ye olde spa store keep telling me 125-150. I am constantly having to add dry acid to keep my ph down when the alk is that high. The alk drops anyways after adding acid and then they want me to add alk increaser. It would make more sense to me to keep total alk lower and avoid having to add so many chemicals all together. Fwiw I'm using the spa frog system. I know it's more expensive than chlorine or straight bromine but so far it is mighty convenient and easy. Any input?

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
The people at ye olde spa store are wrong. You will have a slower pH rise and add less acid if you maintain a lower TA level. Caldera is right that you shouldn't go below 40. Why don't you let it go down to 60 ppm and see if the pH is stable enough for you. Also note that lower pH has more carbon dioxide outgassing which causes the pH to rise so target a higher pH level, say around 7.7 or 7.8.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
It's called the Merry-go-round.

You add TA. Spas have a lot of aeration, so pH climbs rapidly. You add acid to lower pH. The acid also lowers TA. So you need to add more alkalinity. Repeat.

And you've just created one wallet-draining lap. I'll bet you've been buying Alkalinity Increaser at ye olde spa shoppe, which is just repackaged baking soda at four to five times the cost in a grocery store. For the exact same chemical. Exact. Odds are very good that if you keep adjusting pH down, when the TA approaches 70 or so, the pH will take a long time to rise again and it may even hold steady for a week or two at a time.
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