Wort Aeration ~ A Do-It-Yourself Approach
by Ron Hamm
Wort aeration is an area of homebrewing that I believe most of us neglect woefully. After a long hard day of brewing the perfect batch, the last thing you want to face is doing the rock-n-roll with a carboy or two full of sweet wort, trying to add a little oxygen to the mix in order to give your yeast a fighting chance at kicking off and surviving the initial shock of pitching. Still, it is an area that is very important to a successful end result.
There are several commercial solutions to the problem, such as the Oxynater™, Oxygenator™, and others of their ilk, that provide you with some form of regulated input from essentially pure oxygen tanks, via a diffusion stone or some other device. While I find these admirable, I also believe them to be overly expensive, if not, overkill.
Being a gadget freak who likes to know intimately how things work, my solution is to build-it-yourself. Here's what you'll need to construct a rudimentary aeration system. An aquarium pump (small and cheap is fine, just make sure it has enough outflow to pass through the filter), a 4 to 5 inch length of 1" to 11/2" D PVC pipe, a couple of PVC end-caps to close off the pipe, 2 threaded hose barbs, sufficient plastic tubing sized to mate to the hose barbs and to reach the confines of your fermentation vessels, some aquarium filter floss, a small carton of good grade activated charcoal, and a diffusion stone like those at DeFalco's. I cannot recommend the little blue diffusers that you'll find at the fish supply store. They are pretty brittle and I wouldn't want it breaking up in my wort.
Put it all together as follows. Drill a hole in each PVC end-cap slightly smaller in diameter than the hose barb threads that you're using. Screw the hose barbs down tightly into each end-cap. Place one end-cap on the length of PVC pipe and pack a wad of aquarium filter floss into the open end, pushing it down tightly into the inner part of the attached end-cap. Pour activated charcoal into the pipe, until it nearly fills the length of the pipe. Tamp it down some (it settles), and refill as necessary. Next take another wad of filter floss and place it into the remaining open space in the pipe(it should actually extend out of the pipe, finally placing the remaining end-cap on the open end of the pipe. You want a nicely packed cylinder. If it rattles, I'd redo the filling to take up the slack. Attach the tubing to the outlet of the pump (keep it short), and the other end of the same tube to one end of the filter. The other end of the filter gets the lengthier tubing with the diffusion stone at the end. Plug it in and let it rip. Mine has a gentle outflow (small pump) and does a remarkable job of aerating the wort. No regulator required. The filter appears to keep foreign materials from entering the wort, and I believe the activated charcoal aids in the cleaning process of the introduced air.
I prepare it for use by immersing the stone in water I heat in the microwave at the beginning of the brewing session. I just let it sit there and bubble the whole time. Prior to putting in the wort for aeration, I'll dip it in sanitizer solution (idophor mix used to sanitize the carboys). It goes into the carboy as I run the sweet wort from the boil kettle and produces some foaming, but not to a level where I have more foam than wort.
It works for me and so far I have not infected a batch by using it. The only change I might make, is to put a little more powerful pump in it when this one craps out and to replace the PVC filter section with a real HEPA filter (if I can ever find one). If you really want to go whole hog, I guess you could feed it from an oxygen tank, but I'd be wary of the pressure you're applying. In my setup, you needn't worry about gluing the caps on the pipe because the pressures are very low. Try it, you'll be glad you did!