So I've got a little 8 gallon mixed reef tank at work. It's a CAD Light AIO tank, the only thing I've switched on the tank is the light, I took out the led it came with and replaced it with a Kessil A80 which has been awesome for the SPS I have in the tank. Live stock in minimum, I've got a Yasha Goby, red candy pistol shrimp, Porcelain Crap, Anemone Shrimp, 2 sexy shrimp and a couple snails for clean up crew.

Recently though I'm getting a green algae at the surface, it doesn't go anywhere else in the tank, just chills at the top, I'm dealing with it right now and I did a black out over the weekend last week and it did get rid of most of it, but it's coming back. Flow is just coming from the return, but I have that up all the way and it's doing a good amount of ripple effect. When I stir it up to try and pull it out with a turkey baster it kind of bubbles in some spots. It doesn't affect anything in the tank coral or fish wise it just looks gross and you can really see it when the lights are off. 

Anyone have a clue what it might be? Other wise the tank is doing fantastic, but this crap comes and goes every now and then. This time I just can't seem to get rid of it. Anyways thanks for the help.