Then I'm not sure. There are no organics in the tank yet, so I'm not sure what the film is. Just trying to figure out what you put into the water is all. Plants don't have any thing on them that would contribute. If you have fish, they would be a source of the film, but you're doing a fishless cycle. If you were using food as your ammonia source, that could also be a source of the film. That's why I was asking. If you don't use Purigien, I would highly suggest it. It does an extremely good job of keeping the water clean. You'll want surface agitation for O2 transfer anyway, but that really doesn't get rid of the film.
Do you have driftwood in the tank?
Love your tanks and they will love you back