My advice when going to pressurized is BE CAREFUL!!! With a yeast+sugar system, it's almost impossible to dump too much CO2 into a tank. With a pressurized tank, you can asphyxiate all the critters to death in less than an hour if you're not paying attention or a needle valve gets bumped or whatever.
In case of emergency, be sure to keep an air pump w/ air stone ready at all times. If you critters start gasping at the surface, a bubbling air stone will drive off the CO2 and increase the O2. I speak from experience, I stunned my fish twice. . . it didn't kill them, but I felt bad about the whole thing.