Sodium carbonate (Na2CO3), more commonly known as Soda Ash, is an additive to raise the pH and alkalinity in swimming pools. Soda Ash has a high pH, somewhere between 11.3-11.7. Those of you reading this who have used Soda Ash may have had it cloud up a pool. This article will explain why that happens, but first let’s explain how Soda Ash impacts pH and alkalinity in water.
 
Specifically, carbonate ions like to become bicarbonate, and vice versa. When you add Soda Ash to the pool, the carbonate anion (CO32-) wants to become bicarbonate (HCO3-). To do so, it needs to get a Hydrogen (H+) from somewhere. When carbonate takes its Hydrogen atom, the pH goes up. This pH and alkalinity chemistry is about equilibrium, so the opposite is also true. When you add acid to the pool, a Hydrogen is released and the pH goes down. It’s all about the hydrogen ions.
Now that we know what Soda Ash is and how it reacts in water, let’s talk about why it sometimes clouds up a pool.