Today I modified my Maxijet 600 to be a CO2 mist machine! I used a small finishing nail to melt only three holes per blade, but they are much bigger holes than a needle gives, and I made sure no holes overlap from blade to blade. Then I took an airline size piece of acrylic pipe and plugged one end with acrylic cement-the high viscosity stuff. Just before it was dry I poked a needle hole thru the center of the cement to get a very small hole for CO2 to bubble through. This I used acrylic cement to glue into a hole I drilled into the intake tube for the powerhead, so it acts like a crude venturi. I connected my vent line from the external reactor to that. It is now running in the tank, giving a faint buzz as each CO2 bubble goes through, and the tank is now seltzer water. The added circulation is still considerable, even with the drilled paddles. Now I need to adjust the CO2 bubble rate so I don't kill the fish.

I like this much better than the Barr Internal Venturi reactor - it is much smaller, no clear tube to grow biofilm on, and it really generates the CO2 mist, with CO2 that would otherwise just sit in the top of the external reactor. I'm a fickle "lover" though, so I may get over this love affair too!