HYDROS BlennyFour Head Liquid Doser and Controller in One The HYDROS Blenny features four micro liquid dosing pumps that work independently to accurately dose liquid supplements, including two part and trace elements for maintaining a healthy aquarium. This controller is ideal for both saltwater and freshwater aquariums, and it can be used independently or seamlessly integrated with other HYDROS devices. The Blenny is capable of sending alerts and notifications,