I washed the walls, floor, and ceiling with water and bleach. This is a step that is extremely important if you are growing in a basement or anywhere else that may be contaminated with mold, fungus, dust, or anything else that could be considered a contaminate.
The water with a bit of bleach in it seemed to work well for me, it got rid of all the mold that was visible in my basement and it hasn't returned yet.
I'm curious to hear about other methods used, so share your info people.