Muriatic Acid Calculator

How to add muriatic acid safely

Always add acid to water, never water to acid. Wear eye protection and gloves, and pour slowly. Add the acid around the deep end of the pool with the pump running so it circulates instead of settling on surfaces.

Never add more than about a quart (32 fl oz) per 10,000 gallons in a single addition. Large doses can drop pH fast enough to make the water corrosive. Wait at least 4 hours with the pump running, retest, and repeat if needed.

Store muriatic acid outside or in a detached, ventilated space. The fumes corrode nearby metal, including pool equipment and anything else in your garage.

Lowering pH vs lowering alkalinity

The same acid does both, which confuses a lot of pool owners. Any acid addition lowers both pH and TA together. The difference is technique.

To lower pH while mostly preserving TA, add a modest dose and let it circulate. To lower TA specifically, use the acid-and-aerate method: add acid to drop pH to around 7.0 to 7.2, then aerate the water (run fountains, point returns up) so pH rises again without raising TA. Repeat until TA is in range.

If both are high, work on TA first. Our guide on balancing pool water covers the full order of operations.

Muriatic acid or dry acid?

Dry acid (sodium bisulfate) is a granular alternative. It is easier to store and handle, with no fumes, but costs more per treatment and adds sulfates to your water over time. Muriatic acid is cheaper and works faster, but demands more care.

The calculator above shows both doses so you can use whichever you have. For a deeper comparison, read muriatic acid vs dry acid.