Oily film on surface

[metalhead]

Well the film is back. I've bumped up my mechanical filtration and will try carbon again once it comes in.

IMHO your problem is not filtration and it definitely has nothing to do with carbon... Keep increasing your flow and surface agitation until the film is gone.

[Carissa]

The reason I mention carbon is because of this:

"The protein skimmer does not remove all proteins from salt water. There are certain kinds of organics that are not efficiently removed by the protein skimmer process. These include several of the fatty acid and lipid organics. So besides keeping the protein skimmer clean and working at its maximum ability (see below), the aquarist wants to use some organic adsorbent/absorbent material, such as activated carbon, to remove those other organics that are not efficiently removed by the skimmer. "

What is Water Quality

I know I need more circulation at the surface but I had to move my powerhead back to where it was after I had an ammonia spike. Moving the powerhead reduced the circulation around the rock and I'm thinking contributed to a lack of sufficient biological filtration.

[metalhead]

Carissa... Any updates? How's the film problem coming? Any help from the carbon at all?

[ibefishy]

Just an idea, I have a similar problem with a film developing on the surface in my tank depending on how high the water level is in the main tank. I have noticed if the level is too high the water is pulled into the overflow from below the surface and I get a film building up. If I lower the level of the water in the tank by a tiny amount it starts to pull water from the surface and the film goes away. Sometimes I will raise the water level in the tank so later on I can lower the water level and watch all that film get sucked into my overflows. I have two small air valves that I can open or close depending on how I want the water level. If I close them off completely the overflows drain real fast, if I open them a small amount the water wont drain quite as fast. Its a pretty cool setup for adjustment purposes.
Maybe you can lower the water level in your tank somehow, works for me.

[Carissa]

I'm still having the problem, the carbon hasn't done much to fix it. I find that if the level inside the overflow box is the same as the level of the surface, the film gets worse. I think it's the same thing as described above, it's not sucking the film in. I don't know why my overflow box varies so much as far as how fast it sucks water, some days it goes fast and some days it doesn't; ultimately I think I need a second tube to speed it up. For now I'm going to throttle back my pump a little to give my overflow box the edge again, and see what happens. I'm pretty sure that's the problem now, the pump is pumping a bit too fast for my overflow.

[Carissa]

It worked. Decreasing my pump flow allowed the overflow box to start sucking surface water, film is now gone after about 5 minutes. Guess I need to get better flow through my overflow box to maximize my pump's capacity.

[metalhead]

It worked. Decreasing my pump flow allowed the overflow box to start sucking surface water, film is now gone after about 5 minutes. Guess I need to get better flow through my overflow box to maximize my pump's capacity.

Good deal!