<div>The 882ppm CO2 treatments was achieved by using an Aquacontroller (Neptune Systems) controlling solenoids (Peter Paul Electronics) that injected CO2 into one header tank per six experimental tanks based on the pH detected in the header tank. Present day air was dispersed into the water of the 444ppm CO2 header tanks at 4 l/min. Alkalinity titrations were performed twice weekly on a water sample from each experimental tank (T50 titrator, Mettler Toledo) with pH, salinity and temperature recorded in each tank at the time of water sampling. Carbonate speciation in each treatment (Table 1) was calculated using a bespoke R-Script (Putnam and Silberger, unpublished). Based on titrations performed at 6 hour intervals over one 24 hour cycle, pH, CO2 and alkalinity were relatively invariant between day and night. <br></div>