What you use will depend on if there are plants currently living in there. I clean my rooms constantly and once per year I do a complete sterilization of the rooms. First I remove all the plants from the room. I use a solution of bleach and water and wash down all the walls floors and ceilings. I also wash down all racks, tables and fixtures. I rinse everything twice. I run fans in the room until I no longer smell the bleach. I have never had a problem with mould, mildew or pests. A little preventative maintenance goes a long way. I grow in soil and it is easy enough to remove my plants. Hydro growers that are perpetually growing may have to go about this another way.