oh yeah, the film on the top of tank isn't real bad. It's actually kind of benificial. That film occurs because of the lack of surface aggitation. I'm sure you knew that. However, in a planted tank surface aggitation isn't usually a good thing. Well, the surface aggitation allows for oxygen to transfer into the water and it releases co2 from the water. So, if your fish are looking like they are suffocating without the surface aggitation, then then surface aggitation is good (at least temporarily), if the fish are breathing fine without the surface aggitation, then having a still surface will benifit the plants. As you probably know, they more co2 the plants consume the more oxygen they can produce. So, in essence, in a well planted tank, there is no need for surface aggitation other than aesthitics. In that case you can get a surface skimming attachment for your canister like the Tom Aquatic Surface Skimmer...
Tom Aquatics Aquarium Surface Skimmer
You may be able to find a better price, I didn't really look at prices.