If it is blue-green algae (the bacterial 'algae', cyanobacteria, slime algae) I got rid of mine by syphoning/scraping up all I could see up (It was mainly on sand and glass), cutting back all infected bits of plant, adding an airstone as the ventilation was going to be reduced, then covering the whole tank with aluminium foil (baco!) for three whole days. No peeking, feeding or cheating. After 3 days I did a large water change (50%) and again syphoned up anything that might have been dead slime. Fish were fine, plants were fine, haven't had any cyanobacteria since. That was about a year ago.
I did read that you can get rid of it with antibiotics but the method I used is the chemical free route. And all you need is bacofoil and patience.
Cathy