03-23-2005, 07:24 AM
Join Date: Jan 2004
Location: Miami, FL
iTrader Positive Rating: 100%
I used to experience this as well. I'm not sure but I think when you bubble CO2, the bubble exchanges the CO2 for other gases present (e.g., N). You then end up with bubble accumulation that may be composed of N, O2, whatever. When this gets to a large enough size, the filter burps it out.
That's how I thought about it anyway.