Film on top of water

There is a cloudy film on the top of my tank. There are also these green bubbles on the top and when i touch them, they leave a green slimey residue on my fingers. All my fish and corals look fine though. What is causing this?

 

I'm going to guess your oily residue (which is hydrophobic; it floats on water, and doesn't dissolve) isn't being picked up by your skimmer, because you don't have a surface-skimming overflow. Then, algae is eating it, and growing on the surface.

Prescription: Get a powerhead pointed at the surface to get some agitation, and if possible get a surface skimmer addon for your HOB skimmer.

 

How is your skimmer doing?

 

Not enough surface agitation. Half of my tank has some of that residue as well, because the PH doesn't reach that far.

 

Im not running a skimmer on my tank

 

Skimmers pull out this stuff before it can all settle at the top (like the oil in oil and vinegar), andalgae can eat it. That's the only reason why it's green. Normally, it would have an oily sheen.

 

I agree with adding surface flow, but with no skimmer, what are you running?

 

Fluval canister filter. I have a skimmer and im going to set it up on my tank tomorrow

 

I'd start by making sure your Fluval is clean...

Setting up the skimmer should help.

 

BTW -- How are your water parameters in general?