Green stuff on the water surface !:(

[arash53]

Hi Guys,

Its over two week my water surface is covered with green/brown layer sometimes seems a little bit oily but not everyday , I really dont know what to do ! , everything in the tank doing great dont have any alge issue anywhere in the tank, other than grape macro alge in some area.

My Tank is ReaSea MAX 34G, and I have only 5 small fish and corals.
My protein skimmer died 2 month ago but tank were running just fine without protein skimmer.

Thanks
Arash