On 3 Jun 2004 19:38:21 -0700, (Dances With Ferrets)
wrote:

In the fishroom that I help manage... I had a customer come in tonight
who is serious about his plants, which is cool, but he is doing
something a bit strange that I've never heard of before... he insists
that it promotes better CO2 absorption into the tank water.....

The Nutrafin Natural CO2 system (yeast canister type)... he has the
bubble counter mounted directly under his canister filter intake so
that the bubbles that reach the top of the bubble counter go directly
up the pipe and into the canister filter. Forgive me if this question
sounds ignorant to those of you who are more advanced; but couldn't
this hinder the growth of beneficial aerobic bacteria in his filter as
well as possibly promote the growth of anaerobic bacteria?

Do tell me all the possible benefits or pitfalls of doing this... I
honestly didn't know what to tell him.

Like the others said - no big deal. Good on him if he thought of it on
his own.
It's not going to harm anything, though might be a bit noisy. The CO2
bubble then hits the impeller and gets blasted into so many
microbubbles that it is almost all diffused.
No problem for your nitrifying bacteria either - depending on who you
ask, CO2 will either not force O2 from the water, or will actually
increase the O2 potential of water to allow supersaturation of oxygen.
Either way your filter won't turn anaerobic and try to kill you.