What kind of algae and what are your conditions (water parameters, types of fish)?
If you have a friendly community tank, I recommend otocinclus catfish for a brown algae problem. It depends on how much space you have in your tank. These guys max out at about 1.5 inches. I have a 135 gallon tank. It only takes 3 of these guys to keep it algae controlled. They're much better than plecos, which are lazy by comparison. It's important to do your homework before buying these guys. They can be sensitive and die on you if you don't know how to shop for them. There are several articles online to help.