I have the lotus Sanitizing System that is available at The Sharper Image stores, at home. It is a counter top appliance that comes with a spay bottle and the unit. You fill this spray bottle with regular tap water you place it on the unit. With in 2 minutes you have super oxyginated water that is now ready to be used anywhere around your home to kill bacteria such as mold amd mildew. The way this product works is the super oxyginated water comes from ozone being infused into the water making it 50% stronger and 3000 times faster acting then any chemical, with out the chemical residue. The life expectancy of the lotus water is 15 mnutes then it reverts back to water. I use this product anywhere I want to clean and sanitize, even my little dog"hot dog" follows me around the house helping me clean!.

Regarding tree tea shower sprays, Earth Friendly Products makes one called Shower Kleener and it can be purchased at Whole Foods, Wild Oats, etc.

We spray a 6% concentration of hydrogen peroxide and let that sit for a few moments, then we sprinkle some baking soda and then scrub with a paper towel that has picked up some of the HP. That takes the tub and tile clean to its original state.

If the problem is bigger than the usual family traffic, then I'd wet the whole area with straight 35% hydrogen peroxide and let that sit, rinse and then treat with the above.

We've found that strong hydrogen peroxide beats everything else we've tried on mould.

I have found that Oxo-Brite by Earth Friendly Products is an excellent grout whitener and mold fighter. You make a paste with it and slather it on. Wait at least a half hour and rinse (waiting longer works better). Also, they have a great, lemon scented Creamy Cleanser (like Soft Scrub only non-toxic) and a Toilet Kleener that could be used in pinch on porcelain tiles. Once clean, the Shower Kleener keeps it clean for a long while if used after each shower.