[urbguy]

i know that co2 injection is vital for beneficial plant growth. i've seen alot of DIY projects but the one i found most feasible would be the soda bottle with sugar and yeast. I noticed that all they do is just catch the bubbles and under maybe a bell or a plastic cup so that co2 can dissolve into the water. why all the other fancy stuff if all you need to do is just that? just curious.

 

[Darkblade48]

Methods for passive diffusion (i.e. via a a bell or a plastic cup) of CO2 are extremely inefficient. The amount of CO2 that can be dissolved into the water column is limited by the surface area of the bell that is contact with the water.

In contrast, methods such as glass/ceramic disk diffusers make a very fine mist of CO2 bubbles. These bubbles have a much larger surface area than the single, large bubble in the bell type diffuser, allowing greater and faster diffusion of CO2 into the water column.

 

[timwag2001]

http://www.rexgrigg.com/diy-reactor.htm
here's how to make your own reactor.