Originally Posted by bonzombiekitty
The problem with using starsan is that it foams. Last time I used starsan, it foamed so much that it overflowed the airlock and by the time I noticed it, there was only a tiny bit left.
Initialy I always hook up a blow off tube to a bucket of star san. With the better bottle your limited to a 6 gallon fermenter and I almost always need the blow off tube. Once things slow down a bit I replace the blow off with a 3 piece airlock filled with star san. There is some foaming but it's not so crazy. If the foaming really bothers you, you could use iodaphor.
NOTE: both star san and iodaphor lose effectiveness over time. If you leave it there for weeks and weeks, you should probably replace the star san / iodphor every so often.
If your using a glass carboy your probably fine with regular water in the airlock.