Difference Between Dry Acid and Muriatic Acid

The key difference between dry acid and muriatic acid is that dry acid is comparatively safer than muriatic acid to be used in swimming pools.

Dry acid and muriatic acid are inorganic acid substances whose chemical structures contain cations and anions bound to each other. These two substances are very important in maintaining the water balance of pool water.

1. Overview and Key Difference
2. What is Dry Acid
3. What is Muriatic Acid
4. Dry Acid vs Muriatic Acid in Tabular Form
5. Summary – Dry Acid vs Muriatic Acid

What is Dry Acid?

Dry acid is the common name for sodium bisulfate. Usually, it is produced in granular forms which have a white, dry appearance. Manufacturers use sulfuric acid and sodium hydroxide and mixing these two substances results in dry acid consisting of the salt sodium bisulfate and water.

Dry acid is very important in swimming pools where we can use it to lower the pH of pool water and decrease the total alkalinity. Adding this substance is helpful in maintaining the water balance in pools having a high pH or total alkalinity. Moreover, we can store this substance in a wide range of conditions, but it must be handled carefully because it is corrosive.

Figure 01: Pool Chemicals

We can add dry acid directly to pool water (well-circulated pool water) where the granules of dry acid can readily dissolve. However, we need to immediately check for swimming pool pH prior to the addition and after about 6 hours of addition.

What is Muriatic Acid?

Muriatic acid is a solution of hydrochloric acid with impurities. Therefore, it has the same chemical formula as hydrochloric acid, which is HCl. Although hydrochloric acid is a colourless substance, due to the presence of impurities, this substance has a yellow colour. This yellow colour arises because there are traces of iron as the impurities.

The production of muriatic acid involves the distillation of hydrochloric acid and a salt (containing chloride ions). The impurities in this acid come from this distillation process. However, these impurities do not affect the properties of the acid. According to the Baume rating, this acid has a lower value when compared to hydrochloric acid. The Baume rating scale is a scale used in measuring the density of a liquid.

Muriatic acid as a cleaning agent has many uses; to adjust the pH of the swimming pool water, to clean the metal surfaces (as the acid strength of this compound is low, it is not enough to melt the metal surface), etc.

When considering its application in pool water, it is helpful in maintaining the water balance of swimming pool water where we can use it to balance the pH of pool water. Compared to dry acid, it is less safe because it can cause damages to the surface when spilt or splashed accidentally on surfaces.

What is the Difference Between Dry Acid and Muriatic Acid?

Dry acid and muriatic acid are inorganic acidic substances that are helpful in balancing the pH of pool water in swimming pools. Dry acid is the common name for sodium bisulfate while muriatic acid is a solution of hydrochloric acid with impurities. The key difference between dry acid and muriatic acid is that dry acid is comparatively safer than muriatic acid to be used in swimming pools.

The below infographic tabulates the differences between dry acid and muriatic acid for side by side comparison.

Summary – Dry Acid vs Muriatic Acid

Dry acid and muriatic acid are important components that we can use to balance the pH of swimming pool water. The key difference between dry acid and muriatic acid is that dry acid is comparatively safer than muriatic acid to be used in swimming pools.