How much TA reduction with murayic acid

MNPoolDreamer · Jul 17, 2011

So far the bbb method has been going well. The only part that is my battle is the high TA and calcium hardness.

Here are my results today - from pool store they do a pretty extensive testing not just strips.
Tc - 4.6
fc - 4.6
PH - 8.2
TA - 240
ch - 325
Cya - 20
Borate - 30
Tds - 400

Their recommendation was close to pool calculator of 11 pints muratic acid. My question is is the amount more for the ph or the TA? How much of a decrease will there be in TA? Also, they say to only add 4 cups every 4 hours of ma. What happens if I don't wait? I already added 8 cups - four at a time 3 hours apart. Ph is still high.

Thanks. I feel like this TA is going to be my never ending battle. It is with the fish tank!

Pool is 13500 gal, 2 hp pump no heater yet.

JamesW · Jul 17, 2011

Use the pool calculator to determine how much 31.45 % muriatic acid you need to add to lower the pH from where it is to 7.2. Add the amount of acid and then retest after 1 hour. Continue to lower the pH to 7.2 until the TA is where you want it.

Going from 8.2 to 7.2 in 13,500 gallons with a TA of 240 and a borate of 30 will take 133 ounces (about 1 gallon) of acid. 133 ounces of acid will lower the TA by 39 ppm.

pool-school/lowering%20total%20alkalinity

bobodaclown · Jul 17, 2011

Hello,
I got my TA down to 80. It was pretty high. Follow these procedures:http://www.troublefreepool.com/pool-school/lowering total alkalinity

When you add the MA ensure your pump is on and pour it in front of the returns so it mixes quickly.

Richard320 · Jul 17, 2011

http://www.poolcalculator.com/ is your friend.

I just plugged in your numbers. To drive pH down to 7.2 will require just about a gallon of acid - that's 8 pints.
Down near the bottom, it gives Effects of adding chemicals A gallon of 31.45% muriatic acid will lower pH by 2.28 and lower TA by 37. So you may not want to add it all at once; maybe half at a time, give it an hour or two to work between doses. And aerate. Also note the disclaimer: Note: pH calculations are not exact. These numbers are only suggestive of the relative magnitude of the pH change you can expect. Small changes, +-0.4, with pH between 7.2-7.8, TA around 80-120, and Borate near zero will be approximately correct. The further you go from those ranges the less these pH changes will correspond to reality.

If a gallon of acid will drop TA by only 37....it's going to take a lot of acid to get it down to target range. So buy 3 or 4 gallons now; it has a long shelf life.

anonapersona · Jul 17, 2011

I see your CYA tested at 20. If that seems to be a valid value, that is, you have not recently added a bunch of CYA and it just isn't showing up on test yet, them you could use trichlor pucks for awhile. It is a luxury, so enjoy it. I suggest you use, your friend, the Pool Calculator, to see how many pucks you could use to get from 20 to 40 ppm CYA. Count those out and stop using that when they are done, go back to bleach. Pucks have the effect of wearing down TA. Or you could save them for a vacation, just know that your TA will be lower after a lot of them.

MNPoolDreamer · Jul 18, 2011

Thanks for the advice of using pucks and not adding all at once. (sorry for the typo, I know it is muratic not murayic!)

I have added 1 gallon over 24 hours, took the cover off and have it areating. Too bad it keeps raining, I should see what the TA is of rain water. It seems the combination of rain and aeration has kept my ph high.

At least I don't have to worry about adding my horrible tap water!

anonapersona · Jul 18, 2011

Rain gives a lot of aeration if it is hard rain, raising pH. It also can give dilution if it is a lot of rain and the pool overflows, lowering TA and thus pH.