Expert: Henry Boyter - 9/24/2005

Question
I have searched google but did not find an answer. For a long time as an Planted Aquarist I have used a mixture of yeast water and sugar to create co2 which we then diffuse into fine bubbles into the water. The dissolved co2 becaomes carbonic acid which all plants need to grow. The issue is that you have to change this mixtur very frequently and it isnt a steady flow. Adding an acid like that brings the ph of the water down, lack of it raises it. swings arent good for fish life.

Now i know that a 10% solution of hydrochloric acid say dripped over limestone will make co2. my very limited understanding is that limestone is also used to netralize acids like hydrochloric acid. So is there danger of hydrochloric fumes entering the water with the co2, or is that a nil point due to the neutralizing ability of the limestone? or are the fumes created only co2?

Answer
Yes you would get HCl fumes in addition to the CO2.  Probably a little hydrogen also. It wopuld be hard to predict how much.  Not only that, it would be nasty in your house and would be a safety issue.

Two questions, CO2 is very insoluble.  Is there not enough in bubbled air?  Also, a tank of CO2 or some dry ice might actually be more economical and a heck of alot safer and VERY reproducable.