Periodic flushing of the laser cutter water chillers has revealed a problem with build up of algae type growth which has the potential to block the flow of cooling water, shorten the life of laser tubes and damage the chillers. This problem may be mitigated or prevented by use of an algae killing UV filter - Fluval UVC In-Line Aquarium Clarifier - target $129. + $9.50 delivery $138.50