ZEP Mold and Mildew Stain Remover is likely the handiest cleaning product on my boat. It is pretty much the same stuff as Tilex but half the price. It really works great.
--The green slime that grows on the motor when it has to be left in the water during winter? I tip it up, use the hose to blast off the big stuff, wet it down with ZEP and let it almost dry, rinse it, and then wet it again with ZEP and tip it back down. Cleans it completely.
--The slime that stays on the bottom paint when I pull the boat? I don't like to scrub the bottom paint, but the ZEP lets me rinse it off clean.
--The mold that gets on the hoses for the head and in the nooks and crannies you can't really scrub? Spray the ZEP on and forget it. It's all clean and white the next time you look at it.
--The discoloring that gets on the non skid surfaces and the cockpit floor? ZEP and a hose rinse, no scrubbing.
--The crud that builds up along the edge of the rub rail and in the window tracks? Well, you get the picture.
If I sound like an advertisement for the stuff it is because it really is that good. I have a small pump up spray bottle always ready to go and a spare gallon in the boat. When I pull the boat out of the water for a cleaning, I use a weed sprayer and wet it all down with the stuff before I wash it. Works amazingly well. I don't know what it is doing to the environment but it works good.
Home Depot has it by the gallon.