OK, so I've scoured various threads and other sites and can't find a clear answer to another (rather obvious) question from a credible source. If you have a big old canister filter, why not feed the co2 into the inbound hose? Wouldn't the impeller and all the travel through the hoses and media etc. mix it up nicely with the water so when it comes out into the tank it is dispersed? I'm guessing one possible answer is that the co2 level in the filter might muck with the bacteria. Maybe there is something even more obvious. I read something about voiding warranties but that doesn't really pass the "so what?" test... Thanks for any answers!
Most people have or, will try it at some point. It will work as you would expect but, the CO2 will also accumulate into large bubbles inside the filter and then belch out the bubbles every once in awhile. It becomes annoying to see and makes you think you are wasting CO2. Maybe not the best solution but, will work until you put together a better solution.