Film on surface

I have 2 cubes, a aquatop 21g and a bio14. With the 21 I have been getting a film on the surface. While with the 14 I dont. When I do weekly water changes I try to suck as much of it out as I can but it comes back. Has 3 media baskets, I ditched the bio media. Using filter floss, purigen, chemipure elite and phoszorb. I looked at it and it looks like its not skimming the surface, it does have a skimmer. Has a removeable intake grate and I tried without it and it didnt change. Curious if anyone might have some suggestions.

 

Skimmer pulls from the back of the tank. Ive even removed the intake grate and the film goes no where. The first chamber is full, just as full as the tank. Then it flows from the bottom up through the second chamber then overflows into the third with the return. I have the return and circulation pointed up to try and break it up but you can just see it blow a hole and it fills back in. I read a little and most say is disolved organic compounds. Need something to skim the surface. Listed a few chemicals to use or water changes. Any small skimmers that would fit and skim the surface. I noticed this in my QT tanks, no skimmer, and only a sponge filter. When I would turn the pumps off you could see a film. I added a HOB and it was gone over night.

 

I have. Facing the tank the return is in the upper right corner, overflow is the upper left corner. I have the flexible joint curved to blow to the left and pointed up. Powerhead on the left pointing up. You can see the powerhead and return blow a "hole" in the film but it just fills back in, powerhead is a wavemaker on pulse. I had read other people had issues with the water level and the overflow grate, needing to create a actual overflow. You can look from beneath the surface at the overflow and there is no water movement. Needing to get the the water surface to flow over.

 

I took another look at this. The intake grates/panels are removable and sit in a little slot. Theres 2 that are slotted and several that are solid. If you put a grate in the bottom you cant put in a substrate as it will suck it in. So I did a solid, grate, filled with solid then a grate on top. This the panels removed there is a fixed divider about a 1/4" behind where the panels go. But what I tried was pulling the panels out and putting both grates at the top so it would no longer be pulling any water from the bottom. After doing this I could see a slightly more noticable overflow and some of the film going in. But its like theres not enough flow. Before I could suck out the film and it would take a day or 2 to come back. Now I can suck it out and its back as soon as I turn the pumps back on. Could my media be blocking the flow? Do I need carbon and purigen or should I stick to 1? Would floss on the intake help with particle removal? Was going to try blocking the intake and trying to make the water level raise and overflow but I dont have anything big enough to cover it.