I have tried just about everything for bedding, here's what I use now
Boys: hemp bedding with a layer of timothy hay, this is the best for stinky boys.
Girls: I use kiln dried spruce(kiln drying removes the harmful oils in wood)
The play tank was yesterdays news cat litter, which is recycled newspaper. I used it for a while in the tanks, but really didn't like the way it smelled. The spruce has no smell at all, and it keeps the tanks smelling good.