HYDROS BlennyHYDROS Blenny is an aquarium controller with four micro liquid dosing pumps for precise dosing of two part and trace elements. It can handle essential functions for maintaining a healthy aquarium and connect up to four sense port accessories and two drive port accessories. Four 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