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Thread: Fastest way to balance softub with high TA?

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    Fastest way to balance softub with high TA?

    Hello Everyone,

    I have a softub 220. Its time for a refill after being empty for the summer and I had some additional questions. The TA of my tap water is around 375 and calcium is around 275. During initial balancing I have been using dry acid dissolved in water with a separate container. I would put no more than 1/2 a cup in and aerate for 30 minutes. It seems to take around 1 3/4 cups total before the ph and ta would be at a acceptable level. I don't have the exact numbers as its been a while since I filled it. This takes a very long time but I wonder if even 1/2 cup is to much at once? Whats the max I should be putting in and how long can I wait between doses? I would like to switch to the half strength muriatic acid since my ta is so high but was wondering if that would be safe on the vinyl if its mixed with more water?

    My other question is what is the easiest way to figure out the exact amount of water? I'm thinking 220 is being filled to the brim and I just need to figure out how many gallons per inch so I can do a better estimate with how far the water is from the top. Other than that I'm thinking of buying a scale so I can do more precise measurements with the initial dichlor or any other powdered stuff I might need to use.


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    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Fastest way to balance softub with high TA?

    You should only add enough acid to lower the pH to around 7 ... you should not lower it further than that. So, test the pH, use Pool Math to calculate how much to add to lower the pH to 7 this will also lower the TA some, the aeration will then raise the pH back up and allow you to add more acid. See pool-school/lowering%20total%20alkalinity

    There is no problem using muriatic acid ... even the full strength which likely costs the same ... you will just use less of it.
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  3. Back To Top    #3

    Re: Fastest way to balance softub with high TA?

    thank you. I have read it so many times not to go below 7.0 but this helped it click for me.

    If I'm understanding correctly the acid mixes in and lowers the ph faster than the aeration can raise it back up so this is why we need to wait and use smaller amounts so not to drop below 7? I was also wondering if the TA of my tap water stays the same will the process stay similar for each fill? I guess what I'm asking is if its safe to skip a few ph checks during this balancing process once you have the safe dosages figured out?

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    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Fastest way to balance softub with high TA?

    Don't worry much about TA, it really is a fine tuning issue, and on such a small body of water not much of a concern at all. As to calculate volume, there are a number of online calculators for volume of a vertical cylinder, just measure average diameter and depth of water for the measurements (assuming round tub)


    p.s. here is a link to one, answer is a litres, but there is a litres to gallons converter at the bottom of the page
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    Re: Fastest way to balance softub with high TA?

    Well everything I've read and from my own use the TA has to be something like 50 - 60 for the ph to be correct and stay balanced with all the aeration. Or maybe I should say that is the end result after balancing. It takes a afternoon of messing with the tub on a refill since my tap water has such a high TA and I was hoping there was a faster way but as you guys have pointed out I was probably adding to much acid at once already so it may take even longer.

    Thanks for sending me in the right direction to the volume calculators. It seems the 220 capacity of the tub is not calculated from the top and is a realistic max capacity. However with 2 people using it the water level will be a bit lower and more like 190 - 200 gallons. This should help a lot now that I have a more accurate capacity to plug in. I was estimating around 175 gallons before.

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