how the beep beep beep do i get rid of an oil slick at top of tank

[Zoaelite]

Originally Posted by Milad

got some water already mixing!

but what the hell could be causing it. could overdosing ZEOBak be the problem?

Skimmer intake could be blocked, I would give it a good clean. I think if you can put your tunzee's on a wave maker you will fix the problem, 30 seconds on 30 seconds off alternating.