Seawater electrolysis occurs when two electrodes are placed in seawater and an electric current is run between them. Water reacts at one electrode (the anode) to produce chlorine and/or oxygen gas (depending on the concentration of ), and at the other electrode (the cathode) to produce hydrogen gas:
- Anode: or
The product of interest is the hydroxide ions produced at the cathode: these react with ions to form , alkalizing the water surrounding the cathode. The alkaline water has a higher concentration of carbonate ions (), which makes it easier for corals to precipitate their own calcium carbonate and grow more easily.