As of Mar 1997, I have been fermenting in corny kegs for 3 1/2 years and about 40 batches. I do both primary and secondary fermentation in corny kegs. The first batch I made, I did the primary ferment in a glass carboy and the secondary in a corny. I have never used anything but corny kegs since and have only had to start a siphon that once. I will never ferment in glass or plastic again, corny kegs are too easy to use and there is no danger of breakage like glass and much less possibility for contamination due to the fact that all transfers are done through sanitized hoses in a sealed environment. ------------------------------------------ Some notes on fermenting in soda kegs ===================================== Both primary and secondary fermentation can be done in soda kegs. When both primary and secondary fermentations are done in kegs, racking is less prone to infection than other methods of fermentation because it is done through a sanitized hose into a sanitized keg and all of it done in a closed system pushed over by CO2. This means that you never have to start another siphon again. A non-obvious trick is to use liquid dip tubes (these are the tubes attached to the liquid "out" valves - the ones the beer actually flows through when leaving the keg) which are shorter than standard length so that when you rack, the trub is left behind. The length to cut off will vary depending on how deep a sediment layer you usually get. I use 1.75" shorter than normal for the tube in a primary fermenter and .75" shorter for the tube used in a secondary fermenter. I use a blowoff tube on the primary fermenter which goes down into a bucket with about 3" of sanitizer solution. It is attached to the gas in valve body which has been modified by removing the inside poppet valve. The poppet valve is the little round thing in the center of the valve body. When you remove the valve body from the keg and look inside, yoy see a triangle with a rivet through it and a spring. This is the bottom of the poppet. To remove the poppet from the valve body, remove the valve body from the keg, place it threaded end down on the floor and use a pin punch to push gently down on the poppet. It will drop down and out.Just get some vinyl hose to fit snugly over the valve body. If you cannot get a tight fit, use a hose clamp, but I have never needed one. The size tubing I use is 5/8", but your size may vary due to the diameter of the valve body (I have pinlock kegs). When sanitizing for racking from primary to secondary, you not only need to sanitize your secondary keg, but the transfer hose as well. This can be done by filling the keg completely with sanitizer solution and then sealing the lid. Attach your transfer hose to the liquid out and open the free end QD (Quick Disconnect - the fitting your beer or gas hose attaches to) fitting (I have made a special adapter for this). Attach a source of hot water to the gas input and force sanitizer solution through the transfer hose until it is completely full and then close the free end. Stop transferring and let it all sit full of sanitizer. When rinsing, be sure to use the same technique with rinse water to rinse out both the liquid side of the keg and the transfer hose. You might ask, why not just soak the transfer hose in sanitizer? Well, you could, but using the hose to let the solution run out of the dip tube and valve body sanitizes those parts, which if you just fill the keg with sanitizer will not be touched because they will be filled with air and prevent sanitizer from entering. Replace the poppetless primary gas valve with a valve body with a valve in it and pressure the primary to 10psi. Purge the secondary with CO2 and seal it up and pressurize to 10psi. Weigh the primary on a scale and take it off. Put the secondary on the scale and leave it there so you will know when the transfer is almost complete. Attach a bleeder valve to the gas valve of the secondary. Bleeder valves are commercially available and are basically a QD fitting with a brass Tee in which are a pressure guage and needle valve. They allow one to measure the *real* pressure in a keg (the guage on the CO2 regulator only registers how much CO2 will be applied, not the actual pressure at the destination). Attach the CO2 from your tank to the primary and boost the pressure to 15psi. Spray off both liquid valve bodies with bleach and then with water. Attach the transfer hose to the primary first and then to the secondary. Beer will begin to flow immediately. Crack open the bleeder valve on the secondary until the pressure drops down to about 7psi, back off the regulator pressure on the primary to about 10psi. Allow the transfer to continue until the secondary weighs about 5 lbs. less than the primary weighed. Put your hand on the liquid QD on the primary and release the lock (on pinlock, turn the ring, on ball lock, lift the collar) while keeping your hand firmly pushing down on the QD to keep it fully engaged. This will allow you to release the QD immediately when the hose begins to suck air. Watch the hose closely and as soon as it sucks air, disconnect from the primary. Reach over and close the bleeder valve on the secondary. While you will usually suck a tiny amount of trub up just as it sucks air, if you leave the transfer hose on after that, the rush of air past the bottom of the dip tube will suck trub in in ever increasing quantities. Racking from secondary to conditioning keg is identical except that you will have a regular length dip tube in the final keg. In secondary fermentation, you can naturally carbonate your beer by attaching a presssure relief valve set at 20 psi. The remaining fermentation will produce CO2 and when it reaches 20 psi, will bleed off as excess CO2 is produced. By the end of secondary fermentation, it will be nicely carbonated. A Norgren 20-50psi pressure relief valve can be obtained from the Surplus Center (800-488-3407). Take the valve apart. Get a replacement poppet from a pin lock keg (maybe ball lock will work, I have not tried it) and hold the top of the poppet with the O-ring in a vise. very carefully with a pliers, grab hold of the little triangle and twist it back and forth until it breaks off. Take the spring and use it in the pressure relief valve instead of the stock one. This will give the valve a range of about 12psi to 30 psi. NOTE: Since this was originally written, I have begun oxygenating with a 2 micron sintered stainless steel stone and pure O2. I use a "carbonation lid" on my keg and run the pressure slowly up over an hour to 20 psi. See my article on making a carbonation lid in Brewing Techniques Sep/Oct 1995 issue. NOTE 2 on Fermenter Geometry: It has been brought up that tall and skinny fermenters are not the ideal geometry and I cannot deny that. However, it only comes into play when you have either insufficient amount of yeast, not optimally healthy yeast, or high gravity worts. I successfully ferment out 1095 worts to 1016 or so. If your yeast is not optimal you may have problems. This is gleaned both from my personal experience and a conversation with George Fix, who pointed out the geometry problem in the first place.