[pogodzib]

Film algae on glass is an issue for many people with powerful lights. Most people just clean their glass every day or two using a magnet scraper. If your water quality is great and you dose minimal additives, you may be able to only have to clean your glass once every couple weeks. I run a lightly stocked tank with a large skimmer and ozone and I only need to clean my glass once every 2-3 weeks, but my tank is an exception to the standard.

BTW - No, your skimmer isn't ideal, but I'm not here to recommend you spend money if you don't have to so I'd just recommend using a magnetic scraper on your glass every day or two unless you are seeing signs of other problems.