An Ode to PET Carboy: Ah, wonderful PET Plastic. Some say it's what's on the inside that counts, but your exterior is what makes you special. You're lighter than glass and if I'm having a bad day and happen to drop you (I'm sorry) you won't break and spread your wonderful home brewed contents across the floor.
Others say "Glass, is the way to go." To that I say no way. Yes, I have to take care not to scratch you when I clean you. But I'm no brute; I'll treat you right.
*Do not fill or clean with liquids hotter than 127 °F (53 °C).
Use carboy stopper size #10 for 3 gallon plastic carboys.