text: The cpFOCE uses replicate experimental flumes to enclose sections of a coral reef and dose them with CO-enriched seawater using peristaltic pumps with computer controlled feedback loop to maintain a specified pH offset from ambient conditions. A cpFOCE chamber has forward and rear flow conditioners on either end to accommodate bidirectional ocean currents. The openings are placed parallel to the dominant axis of tidal currents over the reef flat, and the chamber is anchored with sand stakes. The flow conditioners are attached to maximize turbulence and provide passive mixing of the CO enriched seawater. Four of the tubes in the flow conditioners furthest from the chamber have small holes along their length through which low pH water is pumped to dispense it evenly along the entire width and height of the conditioner. The flow conditioners are also painted white to minimize heating and algal growth. The cpFOCE system was deployed at Heron Island (Great Barrier Reef) to investigate the response of coral communities to ocean acidification.