You may need to wait a little more, if it doesn't start within 6-12
hours there's something wrong. It could be a leak or something with
the mixture. Here's another link that may be of interest to you:

http://www.gpodio.com/diy_co2.asp

Hope that helps
Giancarlo Podio

"Stefano" wrote in message ...
Hi,

I've tried to produce A C02 kit.

After ahow long should I see bubbles coming out of the airstone.
I've had it in 4 hours and nothing comes out.

Could it be yeast not being enough?

Any advice would be appreciated.