The VarioS CR220 DC Calcium Reactor is designed to easily maintain optimal levels of alkalinity, calcium, and trace elements in even the most demanding reef systems. With a focus on quality, design, and precision control, the Reef Octopus VarioS Calcium Reactor series offers 3 different models featuring a new variable speed pump and a unique reverse flow water current design, ensuring maximum water and CO2 contact time with the media. Each model also includes a pH probe holder (pH probe and controller sold separately) to monitor pH levels, as well as built-in bubble counters to track CO2 drip rates. The reactor's design allows for easy removal of the lid, as well as precise control of effluent flow. The solid construction, along with 1/4" quick connect fittings and a 2-year pump warranty, make this calcium reactor a reliable and durable choice. (Note: pH probe not included.) How does it work? By utilizing crushed aragonite,