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CO2 and agitation

This subject is getting me a tad agitated, so thought I would ask the group to
explain what people mean when they say (or imply) that CO2 is lost due to
surface agitation.

Nearly 100% of plant tanks are covered, for one reason or another. My larger
tanks all have glass covers with, maybe, a small cutout for an outside filter.
Those filters, too, are tightly covered.

If I inject CO2 into the water, some may make it to the surface as gas, and some
may just be released to the air above the tank to establish the proper
equilibrium. CO2 concentration in the trapped air is high.

For the life of me, I can't figure out why agitating the surface could cause
*any* significant loss of CO2 under those fairly normal circumstances. The CO2
in the trapped air and the CO2 in solution will still be at equilibrium, and
there is no place for much CO2 to get away.

Even in open-top tanks, the heavier CO2 concentrates on the surface and only
slowly diffuses into the room. *If* you had an active fan blowing air across the
surface, and *if* you did not have any cover, your evaporative losses and CO2
depletion could be high. Otherwise, I'm having a problem understanding what the
problem really is. ;-)


Wright Huntley, Fremont CA, USA, 510 494-8679  huntley1 at home dot com

                  Libertarians prefer to do it free!