The Rio 200 power surface skimmer and CO2+ reactor comes out of the box ready to use as a power surface skimmer. Most aquariums have film build up that is created by dust, algae, fish foods and fats from fish frozen food. This build up reduces gas exchange and good water quality. The dual surface skimmers will prevent clogging form large floating debris and the foam filtering pad will aid in the removal of small debris. In addition the unit can be set up as a CO2 reactor by connecting a carbon dioxides source (not included), now the unit is a reactor that will mix the carbon dioxide with water in the reaction chamber produces an ultra fine bubble for maximum saturation and then dispersed in the aquarium. With Suction cup mounts.