ESV Aquatics Bionic 2-Part Calcium Buffer System for Aquarium The calcium buffer system is a two-component liquid supplement system that is simple, easy to use and the best alternative to a calcium reactor. The Calcium Buffer System maintains calcium and alkalinity levels with no mixing of powders, disruption of ionic balance, or addition of organic chemicals. It helps restore inorganic ions lost from protein skimming and also helps maintain the ionic balance of your aquarium water. The best, simplest and most economical coral reef aquarium maintenance and supplement system to help coral grow and thrive and improve color for your saltwater aquarium.