Pool math: dry acid addition discrepancy vs. clorox dry acid bottle instructions

[richardc]

I measured my TA and it came out to 150, and the PH was at 8.2. The pool math calculations, predicated on 26000 gallons and the aforestated numbers recommended adding 103 oz of dry acid to bring my PH down to 7.4. The Clorox brand dry acid (sodium bisulfate) bottle instructions recommends 50 oz. of their product. That is quite a discrepancy, assuming we are talking about the same chemical, and strength.

Suggestions? Thoughts, Ideas? What am I doing wrong?

 

[mknauss]

Weight or volume? I ran PoolMath and came up with 103 oz by weight or 69 oz by volume.

FYI -- it is a really bad idea to use dry acid. Muriatic acid is much safer for your pool equipment. The Sulfate in Sodium Bisulfate will eventually destroy metal, concrete, etc.

Take care.

 

[Pollock]

I am not a guru here but pool math seems more geared toward liquid muratic acid and you can select the strength of the acid you are using. I would follow the Clorox bottle and might even start out at 30 oz and see where that gets you.

 

[richardc]

Weight or volume? I ran PoolMath and came up with 103 oz by weight or 69 oz by volume.

FYI -- it is a really bad idea to use dry acid. Muriatic acid is much safer for your pool equipment. The Sulfate in Sodium Bisulfate will eventually destroy metal, concrete, etc.

Take care.

Thanks for the tip. I have used about 50 oz. of the Clorox brand of dry acid, following their instructions. I diluted the 50 oz., in water before distribution in the pool. Most likely, I will have to add more, so I will switch to liquid muriatic acid. Is their a certain type or strength o buy? Thanks

 

[mknauss]

The most economical is to buy the highest strength MA, typically 31.45% or 20 Baume. But, some states (especially nanny states) restrict your ability to get that strength and you see 'Green' MA that is 20% or 13 Baume. Typically they cost the same per gallon.

I get mine at Home Depot. 31.45% - 2 gallons - $12.

Take care.

 

[jblizzle]

Does the bottle recommendation account for the TA? If not, that very well could be most of the discrepancy.

 

[cfherrman]

Is there a ta, pH, and borates chart on the bottle?

 

[splashpad]

Thanks for the tip. I have used about 50 oz. of the Clorox brand of dry acid, following their instructions. I diluted the 50 oz., in water before distribution in the pool.

Most likely, I will have to add more, so I will switch to liquid muriatic acid. Is their a certain type or strength o buy? Thanks

Transchem 1 gal. Muriatic Acid(1335100001) - Pool Chemicals - Ace Hardware This might get you on the right track =) (Assuming you have an Ace Hardware dealer near you)

 

[richardc]

The most economical is to buy the highest strength MA, typically 31.45% or 20 Baume. But, some states (especially nanny states) restrict your ability to get that strength and you see 'Green' MA that is 20% or 13 Baume. Typically they cost the same per gallon.

I get mine at Home Depot. 31.45% - 2 gallons - $12.

Take care.

After adding the dry acid according to the bottle instructions, my PH came down to right where I want it at 7.4. However, the total alkalinity remained at 150. I inserted these numbers into "pool math", and no recommendations were given to bring the TA down. Yes? Or am I doing something wrong ? Thank you.

 

[mknauss]

That addition of acid would have dropped TA by 12 ppm based on PoolMath. Might be tough to see with the test as each drop is 10. So aerate the pool and raise the pH back up to 7.8 and then drop to 7.2 with acid and you should be able to test the drop in TA.

PoolMath does not show any recommendations to bring the TA down. You follow this Pool School - Lower Total Alkalinity

 

[Richard320]

After adding the dry acid according to the bottle instructions, my PH came down to right where I want it at 7.4. However, the total alkalinity remained at 150. I inserted these numbers into "pool math", and no recommendations were given to bring the TA down. Yes? Or am I doing something wrong ? Thank you.

There won't be. While it is possible to calculate how much acid it will take to reduce TA a certain amount, adding it all at once may end up lowering pH into plaster-dissolving, eye-burning range.

And unless you are in imminent danger of Calcium scale forming, or the pH bounces back every day, you don't need to go to any special pains to lower TA. As it says in the How-to: "You shouldn't lower TA just to reach a target number."

Poolmath gives a suggestion of 50-90+ . 150 is 90-+. Change the target to 150. Perfect! Next week, if it's 120, make that the new target.