Why not just follow the directions on the side of the can?

"Remove reptile and water from enclosure. Spray substrate, holding can 12" to 15" from surface being treated, at the rate of 1 second per square foot. Ventilate the enclosure well until spray has completely dried and all vapors have dissipated. Replate reptile and water. Reapply this product once a month to prevent future reinfestations."

There's also a ton of over very important saftey information on the side of the can that makes it well worth reading.

-adam