ok so you dont have any fish in there and you want to start from scratch?
The best way to nuke a tank is bleach, one part bleach to 19 parts water, you can do everything with this, then rinse very very well, then fill the tank with water and lots of dechlorinator, and sit everything you have washed with bleach in there, filter etc. for a few hours, then rinse rinse rinse again.
id buy new filter media and air tubing, and anything else that is cheap and easy to replace.. you can put your gravel in a sauce pan of water and boil it, that will kill anything in the gravel.
then set it all up as if it was new, and start cycle again. then you can get fish in a few weeks.