Thanks. Do you diffuse CO2 into a canister filter? -Bruce Geist

I used to, but I had a problem starting my Fluval 203 canister sometimes
when the bubble flow was too high. I've got scared that someday the filter
would stop in the middle of the night and all the bacteria would die. Plus I
think it was loosing too much of CO2, so I've switched to Dupla reactor 400.
Awesome gadget! So smartly designed! Had to order it from Europe (I am in
the US myself), as far as I had a trouble to buy one at a comparable price
in the US.

Bottomline, canisters do a decent job if you inject low amount of CO2.
Otherwise I suggest a "real reactor".