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Thread: Total alkalinity question

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    Join Date
    Aug 2015

    Total alkalinity question

    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?
    Caldera Vanto 375 gal
    Taylor k-2106 kit

  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Total alkalinity question

    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.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Total alkalinity question

    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.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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