Yup, Predator and nss1000's right on. They are great. I've got loads of them in my filter pads, and because of that, I am reluctant to ever clean them (the little guys clean it for me).
kris
So I can just live the little guys in my filter pads? I've been brushing them back into the water when I clean the pad. Did some one say they don't even clean their pad?