Diffusion in a shallow tank

[Henry]

I'm having problems diffusing CO2 effectively in my tank due to it being so shallow. With substrate in, I have about 6" of water column. I'm currently using a Hagen Elite Mini, which is doing a good job of making fine bubbles but, even when put right under the spraybar, a lot of them still reach the surface. I've been reluctant to invest in a ceramic diffuser since this will only have the same problem.
The tank is too small for any kind of reactor.

Plant growth seems healthy, but I don't want to waste CO2 unnecessarily.

Is an inline diffuser my only option? If so, what fits an Aquis 500?

 

[mafoo]

Get one of the fluval ceramic ones, they are arround £5-12 and are one of the best diffisers out there.

If you can, put the diffuser on the opposite side of the tank to the outlet so the bubbles get swept down as the water hits the glass like this:

Otherwise, you're probably going to have to go the inline route

 

[Steve Smith]

You could try a cheap ebay ceramic diffuser, and position it at the lower front of the aquarium, assuming this is where the spray bar is aimed. So, the flow from the spray bar should hit the front of the aquarium and be directed down. That down current should hopefully hold the CO2 from the diffuser in the water column for longer in theory.

 

[Steve Smith]

Hah! what Mafo said