The CTgrow HYD-2 Pro+ and HYD-4 Pro+ units require a ORP ezo circuit, which is a small circuit board that enables easy integration of ORP sensors into your HYD-2/4 Pro+ setup. These circuits are required to use a ORP sensor with the HYD-2/4 Pro+ and provide plug-and-play functionality.

CTgrow offers pre-programmed ORP ezo circuits that are specifically designed to work with the HYD-2/4 Pro+. It is recommended to purchase them directly from CTgrow's website to ensure that the circuits are programmed correctly and are compatible with the HYD-2/4 Pro+ units.

The ezo circuits act as an electrical isolation barrier between the CTgrow unit and the sensors. They serve as isolated signal conditioners and converters, allowing for very precise and reliable measurements. This ensures that you receive accurate data from your ORP sensor, ultimately contributing to the health and growth of your plants.