So i installed the surface skimmer yesterday, not 100% sure if its installed correctly but its doing a great job so far. I had a nasty surface scum layer, even bubbles had problems trying to float above it.
Surface skimmers are great, but the underlying problems should be addressed. The majority of the time overfeeding is the cause of it.
Try reducing the amount in a methodical way and that should help. Of course there could be another reason for the problem, but the huge majority of the time it's the volume of food.
Do you notice it gone when you do a water change and how fast does it reform after it?
Not every problem can can be solved by using a certain technique, I have tried everything under the sun to rid of my surface film issue short going the ro route which I wasn't about to do. Underfeeding, bubbler, raising spraybar only pushed film into the corner, did not rid of my issue. The only thing that fixed it was the extractor, been using it for two years now with no problems since the installation.