You don't have use a bubble counter. A better way to measure the amount of co2 in the tank is to use a drop checker. Even if you have a bubble counter, you still need a drop checker. Your bubble rate could be the same as the next guy, but you could have a different amount of co2 in the tank, so its not good to go by bubble rates.
Here is a fancy looking one on ebay:
http://cgi.ebay.com/Chameleon-Drop-C...QQcmdZViewItem.
I have a
Red Sea one and it works great.
If you like to make stuff, you can find links on diy drop checkers just by searching on google. I bought some that someone made and they leaked, so I still need to fix mine. Meanwhile in my tanks without drop checkers, I use this chart:
http://www.rexgrigg.com/co2.pdf. But, I don't check it regularly so I'm sure my co2 levels fluctuate.
You'll want to use a solution in the drop checkers that has a KH of 4. Then you add the indicator solution. When you have 30ppm of co2 in the tank, the drop checker will turn green. Too much co2 and it will be yellow. Inadequate co2 and it will be blue.
Here is a link about them that can explain it way better than me:
http://www.barrreport.com/estimative...s-why-how.html.