Today I melted holes in the blades of the impeller of my little, cheap Catalina powerhead - my hands aren't steady enough to put more than 4-5 holes per blade, and they are kind of randomly spaced. Here is how it looked when I got through:


When I had the powerhead back together I installed a small diameter CO2 line into the suction area and used an airline reducer fitting to get it back to normal airline size. I stuck the assembled unit in a plastic bin of water and ran it - normal flow of water, no suction on the CO2 line. I blew into the line gently and it filled the container with very small bubbles.

It is now in the tank, with the CO2 line hooked to the vent valve on top of my external reactor. About once every 15 seconds a big bubble of CO2 goes to the powerhead and it generates a mist of CO2. I had to rush out to refill my CO2 bottle then, so I'm still not done adjusting the bubble rate to get my drop checker just green. Interesting idea!

I also found that a Rio2100 pump only costs about $35 and you can get a needlewheel for it for $10 - another relatively cheap way to get a needle wheel pump.