DIY CO2 reactor question

[carpguy]

I'm collecting supplies and plans for making a CO2 reactor.

I've seen two different versions of the gravel vac reactor -- one where the CO2 enters at the bottom, and another where it enters at the top. In the version where it enters near the bottom, he mentions that he added a sponge cap to keep the CO2 from being forced down and out by the current. Is there any advantage to having the CO2 bubble up through the flow, or is it going to diffuse into the water as it passes through anyway? Any thoughts?

 

[quick061]

actually if you look they both have sponges at the bottom. the only real difference between those two variations is that one intake is at the bottom and has balls for turblence and the other has the intake at the top but they're virtually the same.

the purpose of a reactor is to disolve the CO2 into the water. you could just put the air line into the tank and let it bubble but then most of the CO2 that you have isn't going to actually disolve in the water before it escapes into the atmosphere. however, if you use a reactor then all of the gas that you input into the system is disolved and doesn't bubble out into the atmosphere.

in this particular reactor to keep the CO2 absorbing into the water they have the rising bubbles fighting against a current. it will work but there are also other methods around.

 

[Richer]

I inject my CO2 via the intake of the powerhead. The impeller chops up the larger CO2 bubbles into smaller ones nicely. The smaller bubbles are then shot into a gravel vac tube, which has a sponge in it. Works quite nicely.

HTH
-Richer