Jimipot this algae is a sign that your cycle is about over. Give us your ammonia, nitrite, and nitrate levels that way we can see if your ready to add a clean up crew. Which will take care of most of the algae.
Most probably a diatom bloom which occurs at the end of the cycle. You can certainly get a clean up crew, but I wouldn't go overboard on it. After I cycled my 55 gal I added 6 crabs and 10 snails (way less than some advise) and still I lost 3 snails, not enough for them to eat. I added slowly after that as I could see they weren't keeping up with the algae. They won't work on the diatom bloom, I got a couple conchs to help with that. The bloom will go away on it's own in a few weeks assuming you keep your water parameters under control. IMO/E you will have diatom blooms off and on for the first few months depending on the water you use and changes you make as you build your reef system. It's all a learning process that needs a lot of patience and research. This board has been very helpful to me. Congrats on what appears to be the end of the cycle....now the real fun begins