DIY CO2 with oxygen

[tiger15]

A traditional DIY CO2 is to put sugar and yeast in an air tight jar to produce CO2 with alcohol as the byproduct. Eventually the alcohol will reach the level to kill the yeast and it is necessary to dump the content and start over. It’s tedious work and a potential danger of accidentally dumping the toxic alcohol into the tank.

What if oxygen is pumped into the jar with an air pump and allow the yeast to digest the sugar under aerobic condition. So it’s respiration, not fermentation with no toxic byproduct or need to replace the content periodically. The process is similar to using yeast to bake bread, simple and easy, just add sugar when it runs out. Will it work?

C6H12O6 + 6O2 > 6CO2 + 6H2O

 

[Zeus.]

But the air being pumped in would dilute the CO2 in the jar so defeats the objective

 

[tiger15]

The jar is sealed and an air pump delivers air into the sugar water to replenish O2 and strip off CO2 into the air space. Another air hose draws CO2 enriched air from the airspace for delivery to the fish tank. The set up is identical to a traditional DIY CO2 except for an extra air hose connecting the air pump to the jar. Because the system is pressurized, the airspace air will automatically pipe into the fish tank.

Yes, the gas delivered to the fish tank is not pure CO2 due to dilution with atmospheric air. But the airspace air is enriched with CO2 that there will be a net gain in CO2 in the tank water.

 

[ian_m]

I think you will find air pump pressure is b*gger all compared to the CO2 pressure obtained necessary to get CO2 going through a diffuser. The CO2 will vent out reverse through the air pump.

 

[tiger15]

You don’t expect any DIY CO2 to generate enough pressure to drive through a ceramic style diffuser so you are limiting to selecting low pressure diffusers. I had set up a fermentation DIY CO2 for a month before abandoning it for pressurized CO2. One obstacle I encountered was the lack of pressure to drive through an airstone suggesting that fermentation pressure is less than an air pump. Another obstacle I encountered was that the air space is dissipated over time as for every mole of CO2 generated, a mole of ethanol is co produced filling up the air space. The same can happen with aerobic DIY CO2 as for every mole of CO2 generated, a mole of H2O is co produced. If there is no airspace left in the jar, there is risk of driving ethenol or sugar water into the tank water instead of CO2 gas.