Raising alkalinity with baking soda
pounds of baking soda = (target − current) ÷ 10 × 1.4 × gallons ÷ 10,000
1.4 lb of baking soda (sodium bicarbonate) raises total alkalinity by 10 ppm in 10,000 gallons. A 20,000-gallon pool from 50 to 90 ppm needs 11.2 lb; a 15,000-gallon pool from 60 to 80 ppm needs 4.2 lb. Spread it across the surface with the pump running and retest after six hours before you add more.
Lowering alkalinity with muriatic acid
fl oz of 31.45 % muriatic acid = (current − target) ÷ 10 × 25.6 × gallons ÷ 10,000
25.6 fl oz of 31.45 % muriatic acid lowers TA by 10 ppm in 10,000 gallons, and it lowers pH at the same time. Dilute the acid in a bucket of water, pour it slowly in front of a return, wear gloves and eye protection, and wait an hour before you test again. Once alkalinity is in range, set your chlorine with the pool chlorine calculator; a salt pool's target is on the salt calculator.
Baking soda (1.4 lb per 10 ppm) and muriatic acid (25.6 fl oz per 10 ppm) factors per 10,000 gallons: Trouble Free Pool, Pool School "Pool Math" and product labels. Read October 18, 2026.
Frequently asked questions
How much baking soda do I add to raise total alkalinity?
1.4 lb of baking soda raises total alkalinity by 10 ppm in 10,000 gallons. To go from 60 to 80 ppm in a 15,000 gallon pool you need 4.2 lb. Add it across the pool with the pump running and retest after six hours.
How much sodium bicarbonate raises the pH?
Only slightly. Baking soda mainly raises alkalinity and nudges pH up a little. For a pH rise alone use soda ash (washing soda): about 6 oz raises pH 0.2 in 10,000 gallons. The pH calculator works it out.
How much muriatic acid lowers total alkalinity?
About 25.6 fl oz of 31.45 % muriatic acid lowers TA by 10 ppm in 10,000 gallons. Dilute it, pour it slowly in front of a return with the pump running, wait an hour and retest before a second dose.
What should total alkalinity be in a pool?
For chlorine pools 60 to 90 ppm, with 80 a common aim; salt pools are often run at 70 to 80 and plaster pools slightly higher. Your CYA counts a little in the test result, so subtract about a third of it for the carbonate figure.
Does muriatic acid lower alkalinity as well as pH?
Yes. Acid lowers both; that is why a pool with high pH and high TA is treated with acid, and one with low TA and good pH with baking soda. Aerating (waterfalls, jets up) then lifts pH again while TA stays low.