Re: Algae Stains
I've done a bit of research on using Oxygen Bleach for everything from cleaning wood decks to cleaning that black algae we get on roofs here in the south. Based on everything I've read, I'd try the following:
6 oz. Shout Oxy Power (Marketed by SC Johnson). This product contains 75% sodium percarbonate (a.k.a. oxygen bleach, the active ingredient in OxyClean type products). This is the highest % of sodium percarbonate you'll find in readily available Oxygen Bleach type products (OxyClean contains 50-60% sodium percarbonate). Oxygen Bleach has a good rep for killing algae & other organic growth while being alot safer than chlorine bleach.
3 oz. diswasher detergent (adds a surfactant for general cleaning that won't foam & make using a sprayer more dificult).
1 gal hot water.
Mix & allow 5 minutes or so for everything to disolve well.
Spray the boat bottom with the mix using a pump type garden sprayer. Let it sit for 10-15 minutes (keep damp by respraying as neccessary) to allow the oxygen bleach to kill anything organic on the boat bottom.
As necessary, rinse off, pressure wash, or scrub bottom using the most convenient method (push broom?).
This is recomended for cleaning decks as well. The oxygen bleach doesn't break down the lignins in wood like chlorine bleach does, is safe on plants, & is much safer than on the environment in general.
I've used this on decks with good success; if anyone tries it with difficult algae on their boats, please post back with your results.