I have tried many different products for substrates and found most to be unsatisfactory. A couple months back Scott Felzer wrote an article about garter snakes for Reptiles Magazine. In his article he talked about substates and recommended Harlan Teklad Tek-Fresh Bedding. It is bedding for use with rats and mice. I have been using it now for a couple of weeks and it is GREAT stuff. I can't tell you exactly what it is, but it looks like the material they make egg cartons out of with a few woody fibers. This bedding is incredibly clean. The snakes stay very clean. It is easy to spot clean. A bag goes a long way. My snakes tunnel in it and it works for small as well as the bigger bulls.
If you cannot find a local source contact Mary Harland at:
MMKnudsen@aol.com. She has been very helpful.
Mike B.
Ron