Apparatus is provided having a signal processor or signal processing module configured to receive signaling containing information about the quality of water in a ballast water tank recirculation treatment system, e.g., in a vessel, boat or ship; and determine information about a variable fluorescence treatment to the water in the ballast water tank recirculation treatment system, based at least partly on the signaling received, as well as provide corresponding signaling containing information about the variable fluorescence treatment. The apparatus may include a variable fluorescence device configured to receive the corresponding signaling and provide the variable fluorescence treatment, including providing ultraviolet (UV) light to the water in the ballast water tank recirculation treatment system.