Do enzymes impact the pH of the water by off-gassing carbon dioxide?

Enzymes create CO2 bubbles as a byproduct of breaking down non-living organics and oils. But does that raise the pH because CO2 is leaving the water?

The carbon dioxide (CO₂) that enzymes release will off-gas from the water, but will not raise the pH of the pool.

This is a great question that we have received. We have been teaching about the relationship between pH and dissolved CO₂ in the water, and how Henry's Law of the Solubility of Gases comes into play. In short:

The amount of dissolved CO₂ in the water impacts the pH of the water. The more CO₂ dissolved in water, the lower the pH, and vice versa.

↑CO₂ = ↓pH

↓CO₂ = ↑pH

It sounds logical that the CO₂ bubbles created by enzymes would raise pH as they leave the pool. But they don't, because outgassing CO₂ as part of the carbonic acid/carbonate alkalinity equilibria is what determines your pH. The CO₂ that enzymes release was not part of the carbonate alkalinity in your pool...it was in the form of carbon bonds holding together non-living organics and oils.

So when enzymes break down organics, the CO₂ released had nothing to do with the pH of your pool. In other words, it does not impact the percentage of carbonic acid (H₂CO₃) in your water. The illustration below was created by Robert Lowry, and he gave us permission to repost it:

The CO₂ in this buffering system has nothing to do with the CO₂ released by enzymes.

Enzyme bubbles

CV-600 and CV-700 create bubbles when they do their job. The most noticeable bubbles are shortly after purging the pool when the most organic contaminants are in the water. Weekly doses rarely show bubbles. 

The initial suds are from the surfactant in the enzymes, but shortly thereafter you will see clusters of microbubbles on the surface. Those small clusters of bubbles are CO₂ reaching the surface and off-gassing. These CO₂ bubbles are evidence that the enzymes are working. They are harmless and should dissipate within a couple of days. Just let the enzymes do their thing.

Aeration boosts enzyme activity and promotes more CO₂ off-gassing. Clusters of tiny bubbles like these are a good thing! The enzymes are working.