Baby oil is effective in shining stainless steel and aluminum surfaces and removing fingerprints and water marks. To use it, apply a little to a soft cloth and rub it over the silver-colored parts on the hot tub. Avoid getting it in the water, but if you do spill a little in the tub it is okay, as the chemicals in the hot tub will neutralize the oils and the filter will remove them.
Purchase a commercial metal polish and use it to clean the silver-colored parts of the hot tub. Be careful not to use any commercial polish that contains toxins in areas that are near the hot tub water. In these cases, use the polish on the outside of the hot tub only.
White vinegar will remove water spots and fingerprints to help make the stainless steel or aluminum shine. White vinegar is also completely non-toxic and natural and it will not harm the water if you accidentally get it in there. To use it, apply a little to a clean cloth and rub it over the metal until it is bright and polished.
Club soda will also work to remove stains from the metal so that is appears bright and polished. Use it in the same manner as you would use baby oil or white vinegar. Be careful to use unsweetened club soda so that you don't make the hot tub sticky.
Rubbing alcohol is another effective cleaning solution for removing small fingerprints and watermarks. This will make a hot tub shine. Dab it on the silver-colored parts of the hot tub until they shine bright. Be careful, as rubbing alcohol is flammable.