Caribsea Purple Up is a pink and purple coralline algae accelerator and does not promote the growth of nuisance algae. Caribsea Purple up has a unique dual method approach to coralline algae acceleration: Ionic calcium Immediately raises dissolved calcium levels in your aquarium water. Ten micron aragonite targets the live rock surface, where it dissolves in situ (in place), delivering calcium, strontium, magnesium and carbonate right where it is needed. Features: Iodine Replenishment: PurpleUp replenishes iodine, an essential element for coralline algae tissues that quickly becomes depleted in closed systems. Easy to use. One bottle of Purple Up replaces the typical multi-product recipe for successful coralline algae growth favoured by advanced aquarists. Contains Super Sea Calcium, a natural calcium derived from pristine tropical oceans. Treats up to 4730 gallons.