I was told to add one quart of Muriatic acid and completely messed up and added almost an entire gallon! I'm concerned with what is going to happen to my pool since i put to much. What do i need to do to fix it? When will it be safe to swim in again?
Too much Muriatic acid
- Thread starter hija
- Start date
Welcome to TFP! 
It would help if you put the size of your pool in gallons in your signature and posted some water parameters such as the pH and Total Alkalinity (TA) prior to your adding the acid. If I assume you had a starting pH of 7.8 and a TA of 80 ppm, then one gallon of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons would lower the pH to 6.1 and lower the TA by 50 ppm to 30 ppm. This is not good, but not a disaster. However, if your pool is larger, say 20,000 gallons, then the pH would drop to 6.6 and the TA would drop by 25 ppm to 55 ppm.
So depending on your pool size, you can compensate by using 20 Mule Team Borax or a pH Up product (if you already have that) to bring the pH and TA back up.
It would help if you put the size of your pool in gallons in your signature and posted some water parameters such as the pH and Total Alkalinity (TA) prior to your adding the acid. If I assume you had a starting pH of 7.8 and a TA of 80 ppm, then one gallon of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons would lower the pH to 6.1 and lower the TA by 50 ppm to 30 ppm. This is not good, but not a disaster. However, if your pool is larger, say 20,000 gallons, then the pH would drop to 6.6 and the TA would drop by 25 ppm to 55 ppm.
So depending on your pool size, you can compensate by using 20 Mule Team Borax or a pH Up product (if you already have that) to bring the pH and TA back up.