Spray a mild bathroom cleaner around the hot tub, starting above the water line and covering the walls to the bottom.
Wipe down the walls with a wet cotton rag or sponge until dirt and residue are removed.
Rinse out the hot tub with a garden hose until all residue and bathroom cleaner are gone. Refill the hot tub.
Add a natural enzyme to the full hot tub. Pick an enzyme recommended by the manufacturer, and follow its instructions regarding the amount for each use. Turn on the hot tub jets for one minute to allow the natural enzymes to circulate.
Turn off the hot tub for approximately 15 minutes to allow the enzymes to clean the hot tub.
Turn on the hot tub jets for an additional five minutes, then turn the jets off again.
Drain the hot tub. Rinse the hot tub with a garden hose until the walls are clean from the enzymes and residue. Refill the hot tub.