Aragonite precipitations rates of precipitations from seawater, using a pH stat titrator using the constant composition technique between September 2021 and December 2022. Aragonite precipitation rates are estimated from the rate of titrant dosing. Data were collected to determine how changes in the calcification fluids of calcareous organisms affect aragonite precipitation. Data were collected by Giacomo Gardella and Nicola Allison and interpreted by Giacomo Gardella, Cristina Castillo Alvarez, Nicola Allison, Adrian Finch, Kirsty Penkman, Roland Krӧger and Matthieu Clog.