David Marshburn writes:

kush wrote:
: If you can't use a powerhead, you can try snaking the end of the
: diffuser line into the intake tube of your canister filter, or
: whatever. The CO2 will be entirely resorbed into the water by the
: time it comes out the outflow tube. This method will, however,
: make a few filters (i.e., mine) rattle.

Any idea if the same sort of scheme would work for an over-the-back
power filter? I sort of doubt it, but am not experienced with CO2
systems. Maybe introducing the CO2 under the filter media would
work?

I experimented with this last week. I drilled a 3/8" hole in the side
of a spare intake tube for my AquaClear 150, tapered the end of an
airline from my DIY CO2 yeast culture, and worked it in.

It seemed quite effective; I got a pH drop from ~8.2 to ~7.0 in the 7
gallon tank (~6 gal water volume), compared to the ~7.6 pH I get just
letting the CO2 gently bubble out of an airstone. The CO2 bubbles
hitting the impeller made bubbly noises, of course. Also, there was a
fair bit of suction, so be careful if using a soft-walled
(collapsible) bottle for your yeast culture.
--
odoratusque est Dominus odorem suavitatis