my numbers & question about adding muriatic acid


Platinum Supporter
LifeTime Supporter
Jul 13, 2009
Fort Wayne, IN
the numbers are in and they don't look good :(

FC 8.5
CC 0
pH 8.2
T/A 230
CYA 15

The bad news.
I have been battling (and losing) the T/A. Plus, we had a bunch of kids over the weekend and today I noticed algae at the bottom of the pool :grrrr: I am confused how I can see algae, but my CC comes up 0. To add fuel to the fire, I had been adding water due to a leak that is finally found and resolved and got off track with the CYA. So, I thought I had been shocking my pool, but found I have been barely keeping up with the required amount of bleach.

The good news.
The people on this wonderful site have taught me so much that I actually know what is wrong and have the ability to fix it.

Today I plan to add 45 oz stabilizer and enough bleach to get it and keep it at shock level. I need to add muriatic acid, but I'm unsure of how much. If I already start with a high pH, and need to lower it anyway, does the calculator take this into account? Wondering if I should add 47 oz of acid, or 121 oz of acid.

Also, it seems to me that right now everything is off balance. It seems like so many things affect so many other things. Like shocking it with give a false pH reading, and the T/A affects the pH as well. Poor pH, it can't get a break :(

Shower me with your wonderful advice!


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
I get a totally different number for MA when I punch your numbers into Pool Calculator. Just plug in now and target and see what it says. If the acid number looks too high, put in half. You can always add more later.

You will use a lot of acid getting that TA down. You'll add a quart or whatever, pH will drop nicely, then through aeration/circulation, pH will go back up but TA will have dropped a tiny amount. Repeat until you're beyond sure you've done something wrong. You probably haven't. It will come down in time.


Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
East Texas
If your pool needs shocking to clear up the algae problem...........WAIT.......until it is cleared before raising your CYA/stabilizer level any. It will just require a higher level of free chlorine if you do.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida

Your pool is easily correctable.

1. Lower your pH to around 7.2-7.4 or so. Use muriatic acid.

2. Disregard the resultant TA for now. It will come down when you add acid but disregard'll adjust it later.

3. As soon as you get pH down, shock the pool according to the article in Pool School..."How to Shock Your Pool".

If you added the 45 0z of CYA, shock as if your CYA was 50 (20+ppm), or shock at 10-12ppm if you didn't add it.

4. As soon as you have completed the shock process.....

1. Your pool water is sparkling
2. Your CC's are .5ppm or less
3. You can hold your FC overnight without losing more than 1ppm.

Then post back a full set of test results and we'll help you adjust anything that needs it.