How do you lower total alkalinity and pH in swimming pool?

To lower the alkalinity in a pool you can use PH Minus or Muriatic acid. When adding pour into one spot in the deep end of the pool away from circulation, make sure the circulation system is running. Do not apply near metal fittings or near the pool skimmer. Also make sure you follow directions when using the product.

Additionally, there are no directions on a bottle of Muriatic Acid. Use muriatic acid no more than a quart at a time; testing about 20 min. intervals until goal is achieved 80 to 120 ppm. The acid is aggressive but not as bad as Sulfuric Acid ( battery acid) so also be careful where you set the bottle. Even if there is no signs of acid dribbling off the bottom of the bottle it willleave a ring.

Your pH is the opposite side of the same coin with alkalinity.

To raise it use Sodium Bicarb. With the pump motor off and water motionless, add the bicarb in the deep-end of the pool, in one spot.

Let it sit for 4 hours or more. Turn the pump on and allow to circulate for 2-3 hours, then re-test. alkalinity is 80-100ppm, not up to 120ppm.

To lower alkalinity, do the same, just use acid. The chart your need in provided in the link below.