algae on swim platform - how do you get this off?

Hey there,

So like any new boat owner, I'm having to learn all the little things. With the fat sacs in the back of my boat, the swim platform sits under water. So, some algae has gotten on there. It's hard to believe how slippery the wood platform becomes when there's a good amount of algae on there. It is literally as bad as an ice rink! Anyways, the majority comes off with just a scrub brush. However, there is some that is caked on there really really good. I was wondering what the best way to get this off would be. In the past, we've used hydro-chloric acid to get the algae off the side of the boat hull. I'm guessing this acid would not be a good idea to use on the wood though. So, what does everyone use to get this off that you know is safe for the wood?