assuming you have a large enough tank for when the pleco grows (depending on species, of course)

If you want a good algae eater that stays relatively small, look at either clown plecos, bristle nose plecos or a group of ottocinlius. But, it's also a far better idea to determine what it is that is causing the sudden outbreak of algae. Test for things like phosphates, go over the photoperiod and make any needed adjustments. When I moved up to higher lighting on my Discus tank I had a huge outbreak, so I shortened the photoperiod and this helped alot too.

Good Luck,