Think All Pool Acids Are the Same? Think Again
Muriatic acid is one of the most common tools for lowering pool pH, but most problems start with misunderstanding what “strength” really means. Pool acid is often discussed in terms of Baumé, which relates to density and helps indicate the percent concentration of hydrochloric acid. Because muriatic acid is heavier than water, it sinks when poured, which is why dosing technique matters for surface protection. A key takeaway for pool chemistry is that the industry-standard 31.45% muriatic acid behaves very differently than big-box store products that can be closer to the mid-teens in concentration. If you use a weaker acid and follow a calculator built for 31.45%, you may underdose, see little pH movement, and assume something is “wrong” with the water. Accurate dosing depends on matching your calculator inputs to the actual product. Many LSI-based tools and pool dosing charts assume 31.45% muriatic acid, so switching to 15% without adjusting can cut effectiveness roughly in ...