You're complicating things a bit too much. I recently built the cloner detailed here GROWFAQ and it works great, you don't even need to paint it. My air pump is one suited for 10-30 gallon tanks and only has one outlet this is strong enough if you put the water level high enough, all I did was glue a piece of aquarium air pump tubing to connect both pieces of the bubble wand. I didn't get a heater either and it works just fine. I haven't gotten round to figuring out a system to hold the cuttings very well yet though.