alkalinity question

[jmgossman]

Hello all, quick question - I have a 15,000 gallon SW pool. All of my levels are great, except alkalinity, which is about 110 and CYA was between 60-70. I had a little over a pound of stabilizer ~1.3 pounds that I added. So my question is regarding the alkalinity. I know I can dump a bunch of muriatic acid in the pool - according to online calculators it should be about 1.25 gallons of MA! I know that is going to drop my pH and the only way to raise it is with aeration. I can aerate, but Im not sure how long it will take to raise the pH. I have family in town this week and dont want to turn the pool into an acid bath! Will it hurt anything to wait about 10 days until visitors are gone to attempt to make adjustments? Or, would it be better to do it gradually? A quart or so a day of muriatic acid. My pH tends to rise on its own pretty quick after I add MA and hangs out around 7.6 which acording to the charts is in the ideal range. I do some of my best thnking when I am thinking out loud, and typing this, I think I may have answered my own question, but please give me insight!

 

[mknauss]

Welcome to the forum!
TA only is a concern on the high side if it makes your SWCG scale up too quickly.
Be aware you do not add that much acid at once. You lower the pH to 7.2 or so, then allow the pH to rise to 7.6 or higher. Then repeat.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool

 

[AUSpool]

Welcome to the TFP. Just adding to what mknauss said.

There is a difference between adding acid to manage pH and adding acid to lower TA. Both will lower pH but you only aerate to raise the pH after acid if you’re trying to lower TA. When adding acid to manage pH you just add enough to lower your pH to your desired pH target, no aeration required. You only add enough acid to move you pH 0.4 pH units at any one addition. Add acid to water, slowly, infront of a return with the pump on. Test again after an hour and repeat if necessary.

The questions are; what is your desired pH target? 7.8-7.6? What is your pH now? How are you testing?

TFP is about self testing with a decent test kit and self managing the pool.

1.25 gallons is way too much acid. Assuming your at 8.2, 15oz of 31.45% muriatic acid (MA) in a 15000 gallon pool will lower your pH to 7.8.

Wait till your guests have gone to lower the TA and don’t add that 1.25 gallons in one go. When lowering my TA I add just enough acid to take me to 7.2-7.0, no lower. I just let my my pool aerate naturally. 35oz of 31.45%MA will move the pH from 7.8-7.1 in a 15kG pool.

One aspect of TFPC is the FC/CyA ratio. With your CyA at 70ppm and guests you need to make sure you have enough FC to match the CyA. I would shoot for a FC of 7-9ppm.

 

[wireform]

With a TA of 110 it's a non issue. Just deal with regular PH control and watch the CSI number.