Octopus CR100 Single 4" Chamber Calcium Reactor w/screw off lid by CoralVue, Rated up to 125 gal. Reverse Flow Octopus Calcium Reactors are constructed with high quality Cell Cast Acrylic materials and SCH-80 Hard PVC pipes and JG fittings. Great Value and quality construction. NEW FEATURE: Twist-off top cover for easy service. Description: Quality, design and affordability define the Octopus Calcium Reactor series. Available in 3 different models that feature reverse flow water current for maximum water and Co2 contact time with the coral media. All models come with PH probe holders to monitor Ph levels in the main reactor chamber and built in bubble counters to monitor Co2 drip rates. Below is a diagram showing easy setup. * Reef Octopus® 4” Calcium Reactor * Footprint: 9.5″ x 7.5″ | Body Diameter: 4″ | Height: 20″ * Powered by the OTP1000 pump * High quality machine welded cast acrylic construction * 1 year warranty on pump. 1 year warranty on reactor.