this is naturally occuring, I often get this from some of the oils in fish foods, you can either increase your surface agitation which will help knock it down a bit or I've heard you can tear up strips of news paper and lay them across the top of the water( one at a time) for a brief moment then remove them and they'll pull the film up with them. don't worry about the ink in almost all cases it's organic as long as you stick to the black and white and avoid any color pages it shouldn't be an issue