Brewing tip of the month: Keg Fermentations - Tip 2 - Tube Cutting
Continuing along the previous tip of using your corny kegs as a fermenter and using a gas fitting bleeding into a cup of water as an airlock, this tip will help with sediment during keg fermentations.
During fermentation, you accumulate a lot of trub and yeast at the bottom of your fermenter. With a fermentation in a corny keg, there is less area for that to pile up in so it ends up forming a somewhat deeper bed. Since after your fermentation is complete you would like to "rack" under pressure into a serving keg, you would also like to minimize the amount of sediment that you transfer over. The easy way to cut that down is to, well, cut down your "out" tube on your keg. To do this, simply remove the "out" post of your keg with a wrench the way that you would normally remove it to clean it or replace your gaskets. Then pull out your serving tube. This normally goes down to the very bottom of the keg. Measure up from the bottom 1-2 inches and cut the tube with a hacksaw. The higher you go, the less sediment you are likely to get, but the more potential beer loss. So, you may want to start on the low end, run a fermentation or two to see how much sediment you end up getting, then adjust. It will depend on the yeast amount you have as well as how much trub you normally allow into your primary fermentation.
After you are done cutting the tube, you can file down the edges if they are very rough and give the tube a good cleaning (which you should be doing anyway). Then put it back in the "out" post and reassemble your keg. Voila, snap on your airlock version of your gas fitting and you are set to ferment and transfer easily.