04-27-2009, 09:14 AM
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Originally Posted by stevef10
Over the last couple days I've noticed an oily film on top of the water. I'm assuming it's caused by the food we're feeding. All the dry foods we use (pellets, flakes, etc) is made by Tetra. Anybody else have this problem with Tetra? Can you recommend a different brand that won't cause this film??
I am not sure the film on the water results from any particular flake food. Any water surface that is motionless (relatively) will have a film on it, in nature and in aquaria. I have had it but don't now because I have surface skimmers attached to the filters. If the water surface is kept moving by the filter the film will not develop in my experience. However, one has to be careful.
Some fish don't like an agitated surface, especially surface fish like hatchets; I know the books say they will stand motionless in the filter current, but in my tanks I find that when they have the opportunity they stay out of the current and sit quietly in the calmer areas.
In a planted tank, the last thing you want is strong surface agitation because it drives off the CO2 that the plants need.
I have Eheim canister filters and they make a surface skimmer device that attaches as a separate filter intake and there is a very slight "pull" of the surface water that keeps the film from forming but is not sufficient to agitate the water. The only drawback is floating plants that can block the skimmer, or snails that crawl in and when they grow a bit block it.