I wouldn't put 2 in a 10gal tank. I'm not sure i'd put 1 acara in a 10gal personally.
As for the algea, what kind is it? What does it look like? It'd be better to slove the problem and get rid of the algae so it doesn't return then trying to let another fish do it for you. Not to mention the algae eating fish will add to your bioload and make more mess then you want. Hence the reason why i dislike plecos and bottem feeders.
And James, acaras are from South America they are not africans..... meaning africans would not work with them.