I retrofit an out of commission gravel vac for the reactor. I used the top as the water inlet and the bottom as the exhaust. I drilled a hole in the side about 1 inch from the bottom and secured a connector for airline tubing on the inside sticking out with silicone. I filled the tube with clear plastic "tri-beads" from the craft store. I then cut a piece of plastic for the bottom and pre-drilled about 12 holes and siliconed it to the bottom. After the silicone set up, I attached a small water pump to the top of the reactor and airline tubing to connector on the base. Attach the other end of the airline tubing to your yeast bottle. I would rather use a clear reactor so that you can see how much sludge has built up and how well the CO2 and water flow mixes.