# eheim 2213 + eheim diffuser + co2



## slojko (Mar 5, 2012)

Would the co2 diffuse properly if I plug my co2 exhaust into the air input on my diffuser.


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## DKRST (Jan 11, 2011)

The short answer is....sort of.

The CO2 will probably diffuse quite well through your diffuser. The biggest issue is the location of the diffuser outflow. 
If it's near the surface, all those CO2 bubbles will move to the surface quickly, resulting in a waste of CO2 and poor 
distribution down into your tank. Ideally, you want the CO2 bubbling/diffusing near the substrate to provide the 
maximum amount of contact time for the CO2 to diffuse into the water column. A CO2-specific diffuser will give you 
much finer bubbles than an airstone or your diffuser, increasing CO2 diffusion into the water.

The next issue is current flow. You want a good bit of current in the tank to distribute the CO2. I've had my best 
luck in a tank using CO2 with an absurdly high amount of water circulation (there were no fish in the tank, so a strong 
current wasn't an issue). However, if you have too much surface disturbance, then you off-gas the CO2, lowering the
water concentration of CO2.

It's a balance. Take your time and see what works for you. Don't rush it and don't gas your fish. Make small change 
in the CO2, leave it alone for a couple of days and watch the fish. If everything looks ok, then you can up the 
CO2 slightly, wait, observe, repeat. Patience is the key! Remember, too-elevated CO2 will stress the fish physiologically, 
so keep an eye on them.


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