Run it 24/7 like dbot suggested and start out with a low rate. Bps is kind of a sloppy term, but I'm anticipating that you would be just running a ceramic disk glass diffuser in the tank. If so, start off with several seconds per bubble and SLOWLY work your way up. On a tank that small, I'd think you would be maxing out at one bps, again bps is the loose term here. Keeping good surface agitation going to keep your oxygen level up. The breeding will definitely diminish greatly at higher co2 concentrations, so that's kind of your red flag that you're pushing your luck.