In the vivariums section there's a post on wood in frog tanks. I've found articles that say hardwoods are fine, like Bald Cypress and oak, but cedar has too many oils and it might be harmful over a long period.

Sadly there are cons to every type of substrate. If you do a planted tank it will be more expensive (but require far, far less cleaning). A paper towel or reptile carpet will need frequent cleaning.

If you do end up using cypress chips which I don't suggest, then if at all possible I suggest getting some leaf litter to put on top of the chips (magnolia, live oak) and boiling it and drying it out to kill bugs. If you absolutely can't find it anywhere else I might be willing to mail a bag of magnolia and live oak.