Soda Ash vs. Caustic Soda

Posted December 26th, 2015

Soda Ash and Caustic Soda Raise the pH of Acidic Waters:  Which Should You Use?

Two water treatment chemicals are commonly dissolved in water and fed into the residential water stream to increase pH.  They can be fed by the same equipment — a standard chemical feed pump, drawing out of a solution tank.

Here are some issues that commonly come up when deciding which to use, or when switching from one to the other.

Caustic soda is stronger than soda ash.  Ten pounds of caustic soda does the work of 13.5 pounds of soda ash.  Put another way, if you’re mix a solution using 10 gallons of water, you would need to a 5 lbs. of soda ash or 3.7  lbs. of caustic soda.

Caustic soda has the advantage of mixing to a clear solution, but it costs more than soda ash and generates a considerable amount of heat when it’s mixed with water. Soda ash always leaves a residue at the bottom of the container.  In general, soda ash is more readily available from water treatment dealers, but caustic soda can be found at pool supply stores.