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Re: CO2 and trickle filters

>Date: Fri, 14 Jan 2000 13:38:28 +0100
>From: "Ole Larsen" <olet at larsen_dk>
>Yes, but if it is so, the trickle filter couldnīt work fully as intendet
>(supplying more O2 for the microorganisms) ?

I think the answer here is a matter of degree. The media chamber doesn't
get completely filled with CO2 nor does all the O2 become excluded. As the
CO2 laden water goes into the media chamber, some will come out of solution
due to the difference in concentration (yes, removing CO2 from the water).
However, after some time, the CO2 level in the media box rises and less and
less comes out of the water. So, by not blowing air into the chamber, you
reduce the amount of CO2 removed by the trickle filter.   

However, working contrary to this is the fact that air is being brought
into the chamber along with the water from the overflow box (that nasty
gurgling noise). Also, the water in a planted tank generally has hogher
oxygen anyway, providing plenty for the bacteria. So, O2 is being
replenished, providing the bacteria with all they need (amd negating to
some degree the biuld-up of CO2). 

Like everyhting else, it's not an absolute thing like "if you don't blow
air in the media chamber the trickle filter won't work". We've reduced the
efficiency a little to save on CO2. But the plants are helping to provide
more O2. It all balances out.

George Booth, Ft. Collins, Colorado (booth at frii_com)