I have been using a Aqua Clear surface skimmer attachment that goes on the intake of my Aqua Clear 300 power filter. I've had it for over two weeks now and it has greatly reduced the surface film that I was concerned about.
I used to have a slight build up of surface film except where the power filter return flow broke up the surface area. I also had bubbles that would build up at the surface along the edges. Now as small bubbles sometimes rise to the surface they pop intsead of building up in areas.
Because of the increase in particles and film being filtered I have to clean the sponge filter more often. I know it does not do the job that a protein skimmer does but it helped my situation for about a $10 cost.
It did however seem to also reduce the flow rate of my power filter some. But overall I think it helped the water quality in my tank. It's effectiveness may vary depending on the tank setup it is used in but it works well in mine.