I would guesstimate about 2.5 months, based on my 5 lb co2 tank lasting
about 8 months on my 55 gallon.

To my knowledge, very few people use these small cannisters. Also I would
guess it would get rather expensive after a few years.

For lots more info on co2 equipment and low cost sources of supply, take a
look here
http://members.cox.net/tulsaalstons/...Pressure%20CO2

--
Bob Alston

bobalston9 AT aol DOT com
"lawrence zarb" wrote in message
om...
Can someone tell me how long a disposible 500g CO2 cannister should
last in a 55g tank setup?


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