I didn't catch the size of your tank before replying, but I'd definitely recommend getting a pleco. Stick with the smaller growing species (clowns, rubberlips, bristlenoses). Their voracity for eating algae vary fish by fish, but generally, you'll see a dramatic decrease in algae over night. You might also look into snails, pretty much any kind is going to make a big difference. You could try some algae eating shrimp (amanos, cherries, etc), but you won't get the dramatic results you'll see with snails and plecos.
I have one tank that for some reason always seems to have a bit of algae and I just learn to live with it. Granted, it's only on the glass. To me it only becomes a problem if it starts growing on the plant leaves (which will reduce the plants' ability to get sufficient light and to grow) or if it gets thick enough on the glass to prevent viewing the fish. One of the reasons I don't intervene too much is because the algae helps keep a healthy supply of coepepods in the tank, which my fry greatly appreciate.
Also, this is mostly just relevant if we're talking about the green, slimy type of algae and not some of the more unsightly and troublesome hair algaes or brush algaes.