Here is what I am going to try, but I wanted to get some ideas from you guys before I started.
From an old project, I have a Penguin 550 powerhead, good for 145gph or so. I also have 5' of 3/4" clear flixible tubing attached to the output. My plan is to half fill the tube with some cheap aquarium gravel I picked up, and then coil the 5' of hose into a 6" diameter roll, like a garden hose reel. I'll attach the CO2 to the venturi of the powerhead, and viola, a cheap and efficient reactor (or a waste of my time
What can I use on the end to keep gravel in and maintain flow? I was thinking about just drilling a couple of holes and inserting a piece of airline tube perpendicular through the hose to reduce the size of particle that could pass.