The powder form of Natural Calm is magnesium carbonate and citric acid. Adding water triggers a chemical reaction, binding the two together to create magnesium citrate. If you add hot water, this reaction will occur immediately and you will know the product is fully converted into magnesium citrate when the fizzing has settled. If you add cold water, the reaction can take up to 15 minutes before it is fully converted. Neither method yields more or less of a benefit; it is mainly a matter of how promptly you’d like to consume Natural Calm after preparing it.