I point the spraybar on my fluval 404 (DIY made out of PVC) horizontally across the tank, about an inch below the surface. That works well. When I had my 29 set up, I noticed that if the water level was high, the filter didn't create much surface agitation (whisper 60 or something like that) and the surface film appeared. When the water level dropped, the film disappeared.
On another tank, I have a wet/dry sump with a corner overflow, it skims water from the surface plus the output is directed across the tank a few inches from the surface. No surface film.