A third possibility related to #2 happened to me. Too much activity in the
pop bottle pushed the yeat mixture into the tank. A couple 50% water
changes over 3 days and adding some charcoal to the HOT filter fixed things
up. No fish losses.


"Chuck Gadd" wrote in message
...
In that case, it was most likely that the person, using a yeast system
to generate CO2, had the yeast mixture enter the tank. The yeast
mixture pollutes the water, the yeast growing consumes oxygen, etc.

This can happen in several cases:

1) The bottle gets knocked over. Usually by a small child or a pet.

2) When mixing up a yeast mixture, it's common to use very warm water
to properly activate the yeast. If you prepare the mix, and cap the
bottle and connect it right away, you might have problems. The
cooling mixture will contract, drawing water from the tank backwards
thru the CO2 line. This raises the water level in the yeast bottle,
and when the yeast starts really producing CO2, the now higher water
level allows the mixture to get pushed up the CO2 line into the tank.

In either case, lots of water changes can normally save the fish as
long as it's detected soon enough.





Chuck Gadd
http://www.csd.net/~cgadd/aqua