Is mold an issue with Soda?

[Yunus]

I'm just getting into Soda, haven't decided if I'm going with carbonated water and syrup in a pump for each glass or just mix a keg at a time of soda.

How long does a keg of carbonated water last before mold becomes a problem? Are there any additives I could use besides ethanol to extend the life?

 

[yogensha]

I just carbed a keg of RO water to start experimenting with mixing syrup on the fly and was wondering the same thing. I sanitized the keg as usual, boiled the water for a couple of minutes and added it to the keg hot to discourage any growth. Soda water is also acidic, since CO2 dissolved in water forms carbonic acid:

http://en.wikipedia.org/wiki/Carbonic_acid#pH_and_composition_of_carbonic_acid_solutions

For a CO2 pressure typical of the one in soda drink bottles ( ~ 2.5 atm), we get a relatively acid medium (pH = 3.7) with a high concentration of dissolved CO2.

That should discourage most spoilage organisms and molds.