A 9-month aquarium experiment with the cold-water Dendrophyllia cornigera was conducted to investigate the single and combined effects of warming, acidification and deoxygenation on its ecophysiological response. The experiment took place at the Aquarium finisterrae (A Coruña, Spain) between 2022-05-06 and 2023-02-24. Treatment values for each parameter (current in situ vs. climate change) were: 12 °C and 15 °C (temperature); ~7.99 and 7.69 (pH); ~8.63 mg/L and 6.45 mg/L (dissolved oxygen concentration). A total of eight treatments (with 3 replicates each, 5 L aquaria) were set up. Prokaryotes were quantified by flow citometry (CytoFLEXflex S, Beckman Coulter) as previously described by Gasol et al. (1999) with our own adjustment of the scatter settings to more accurately resolve these cells with the new CytoFLEX flow cytometry technology. Measurements were performed every month from different parts of the aquaria setup: the input seawater, the reservoir tank (after the filtration of seawater to 5 µm and before the UV lamp) and every experimental aquaria.