Should work just fine as long as your pressure exceeds the backpressure in the return, which may be trickier in the end.

Most systems like this are on powerheads, with the air line right at the outlet so there is no chance of water feeding back into the air line. I actually use the little hagen elite mini powerhead to initially diffuse CO2 into the tank, but it is aimed as to flow right into the stream of the filter's return spraybar. Takes a little more in-tank, but the powerhead is barely noticeable. Look at my journal in the last post and you will see my setup.

 

I prefer to have the CO2 attached to the inlet of something so that mechanical mixing can occur. You'll get more efficient diffusion into the water that way. works well with needlewheel powerheads, mazzei, some mini filters, plain powerheads, etc. Into the inlet of a canister filter can be tricky, because of potential gas buildup in the filter and the problems that result from that.

 

you could install a diffuser into the output of your filter

 

dj, is that not an INLET strainer? ...and more's the point, why have I not seen those before??!! Fantastic idea!!

Agree with ashappard, you would be best to install your idea on the inlet hose, mkeevil, prior to your canister. You would get much greater dissolution of the CO2..

 

It is in fact an inlet strainer, but it pops right off and is then hooked inline externally with the filter.

 

Putting it on the intake might not be so hot for the impeller/motor. Decreasing the density of the water with CO2 could contribute to burning it out just as running dry. Not sure how it would effect any of the seals. If neither are an issue, it sounds great to me.

 

why don't you just make an inline reactor out of pvc and put that in line with the outflow line? that would be much more efficient.

 

I use a power head with a sponge filter attachment run the air line right into the bottom, and it works great on my 55 gallon tank.

 

That's pretty much what I've got going. I'm pleased with it, but intrigued by dj2606's picture. Where are those available?

-Dave

 

I have an XP 2 on my 46 g and DIY CO2 with 2+ WPG & ferts.
I used to have a HOB rated for 10G on the back as well. I stuck an airstone in to it to diffuse the CO2
A little CO2 would be dissolved into the water but not much.
I took some hard plastic tubing, bent it 90 and stuck the end into the intake of my XP 2.
Now I have to be careful about OD'ing the
livestock, especially at night. I get
30 ppm on my drop checker easily.
If I'm not carefull, the drop checker will "go yellow".
Some folks say you can't OD your livestock w/DIY CO2, but they are wrong.

Charles