I built five individual 3" by 8 " high PVC cells with one inch round by 6" high SS tubes hooked them up in series. Started out with 8 teaspoons of KOH per gallon and then upped the mixture to 12 teaspoons to a gallon. I used a 12 volt battery charger pulling 12 volts, each cell pulled pulled about 2.3 volts and about 4 1/2 amps. I stopped at 12 teaspoons because I didn't gain much additional amps and output going from 8 to 12 teaspoons. Suggest you start with 12 and maybe go to 16 to 20 teaspoons, no heating problems ran the thing for about an hour only went up about 6 degrees and about 1/2 amp. I didn't measure output but my guess would be about .8 to 1 liter per minute for each cell.