On a frag tank that size. i'd just do water changes. skimmers that small are hard to adjust, at least that's been my experience with them. I'd go with a good light source and a good small powerhead to keep detritus from settling. Maybe use mechanical/chemical filtration in the rear chambers, and water changes to control nutrients. My experience with skimmers that small is that the pumps and reaction chambers are too small to be very efficient. I'd invest that money in a solid ATO like the Tunze ATO nano, to help keep the tank stable. It'll keep your ions from getting imbalanced, which is hard to correct when it gets to a certain threshold.
