+1 Sniffles
Even if your parameters are good,algae will supply itself with the nutrients it needs.It does that by trapping and holding the waste and uneaten fish food.
What I would suggest,Is when you do your next water change,do a 20 to 30% change siphoning out as much of the cyano and algae as possible.If you have hair algae,pick as much of that as you can out as well.Then kill the tank lights for 3 or 4 days.Then the day you turn the lights back on,do another 20 to 30% water change,again siphoning out any algae you see.
It may take several times doing that,but you'll eventually get ahead of the algae and be able to control it.