CO2 diffusion via canister filter

[Faust]

I would like to tap in the vast experience of the forumites. I recently set up a planted aquarium and introducing CO2 with three 2L yeast sugar bottles, producing about 3 bubbles every 2 seconds. I plan on upgrading to pressurized CO2 in the near future (budget permitting).

My question to you is the following:

I am introducing the CO2 directly into the intake of my external canister filter. It is an Eheim Classic 2215. The CO2 concentration will thus be highest in the filter. There is no accumulation of undissolved CO2/gasses (The filter starts making a noise when it has not been primed properly, so I am basing my assumption on the fact that there is no sound from the filter). The submerged spray bar also does not squirt out bubbles. My concerns are the following:

- Will current levels of CO2 be detrimental to the material of construction of the
filter. Will the plastic become brittle?
- Will CO2 be detrimental to bacterial growth (lowish pH)

My water parameters are as follow:

pH = 7.5 (prior to CO2 dosing)
kH = 5 deg

[Algae Wizard]

The CO2 should not cause any problem with the filter apart from if you get a airlock in the canister.Dennerle has a diffuser that atomises in a similar way.

If you are concerned get one of these from ebay
http://cgi.ebay.com/UP-CO2-Atomizer-System-for-Plant-Aquarium-8-12mm-Hose_W0QQitemZ370236751831QQcmdZViewItemQQptZUK_Pe t_Supplies_Fish?hash=item5633d47fd7

[f-fish]

Would it not be better to make a venturi cup on the spray bar and let the CO2 bubble into the cup if you like DIY ...

Putting it on the intake of the canister does not feel right - not that I have any canister filters ...

[Faust]

Algae Wizard, I might look into something like that as soon as I upgrade to a pressurized system. Might order one now as we speak...

[Sean J]

I recon it will be bad for the bacteria in the actual canister filter if you induce Co2 in the in pipe of the canister. They are aerobic bacteria and need o2. Co2 might kill them in the filter. It would be better to have the Co2 on the outlet before going back into the tank. That little UP Atomizer is possibly the best bet.

Also, when my canister gets an air pocket, it tends to leak.

[Faust]

Was getting excessive air build-up in the canister filter, it started making noises due to two phase flow in the impeller section. So I decided to resort to a different "in-tank" diffuser, thanks for all your inputs.