just curious
 

How long does a 10lb co2 tank last everyone?

think was about 9 months

I just replaced my first 10lbs the other day....about 14 months. It will be half that time for the next one.

At the height of my coral growth last year I was lucky to get 5 months out of a 10lb bottle.
Right now i figure I'm using about half of what i was but my cal demand has been steadily increasing over the last 2 months and i expect it won't be long before i'm back to what it was

As Marie points out, it depends on consumption. I used to get anywhere from 4 to 6 months out of mine on my old tank. My new tank has very little consumption, so I expect closer to a year until things start really taking off.

for most people what is your bubble rate?

As the controller doses the CO2 based on pH...the bubble rate in my system doesn't matter. When the controller calls for CO2, I think it bubbles at about 2-3 per second.

I used to get about 10 months out of my cylinder when I had an Ocean Aquatics skimmer. Then I switched to a Schuran Pico and the consumption has gone up (which I find interesting as its supposed to be a recirculating model and scavenges co2). Anyway I can go anywhere from 4 months to 8 months on this one.