advice needed with lighting

[stevieduk]

Hi , I got a new double size L.e.d. black box for my reef tank last week.
although my nitrates are barely detectable, since ive had this light ,running it on half power most of the time then on three quarter power for 3 hours in the middle of the day , i get algae seems to apear from nowhere and so many oxygen bubbles rising it looks like a fizzing bottle of lemonade, and then in the evening as it goes down to just the blues, the algae just disappears and the rock and gravel go back to being white again, its so weird. its a reef tank with just two small tangs in so no massive filter load from the fish.
has anyone else had this problem

 

[nautical_nathaniel]

This sounds more like a cyano issue. What color is what you're calling algae and could you post a picture?

 

[stevieduk]

This sounds more like a cyano issue. What color is what you're calling algae and could you post a picture?

its a light film of green that slowly appears. the tangs love it as they are eating away at it for a couple of hours but i get so many fine oxygen bubbles on the rocks that they sparkle, and then when the intensity of the light go down and ends up on blues , it disappears and the green film is completely gone. Ive only had this problem in the last two weeks since i got the L E D s, never had it with T5 tubes , but ive just moved on to acroporas so need more light. As all the coloured Led s are adjustable , i didnt know if i had my colour combination wrong