NOT A FERTILIZER: Purple Up™ encourages the growth of desirable pink and purple coralline algaes not nuisance algaes not nuisance algaes. UNIQUE DUAL METHOD APPROACH TO CORALLINE ALGAE ACCELERATION: IONIC CALCIUM: Immediately raises dissolved calcium levels in your aquarium water. 10 MICRON ARAGONITE: Targets the live rock surface, where it dissolves in situ, delivering calcium, strontium, magnesium, and carbonate right where it's needed. IODINE REPLENISHMENT: Purple Up™ also replenishes iodine, an essential element for coralline algae tissues that becomes quickly depleted in closed systems. EASY TO USE: One bottle of Purple Up™ repaces the typical multi product recipe for successful coralline algae growth favored by advanced aquarists. CONTAINS SUPER SEA CALCIUM™: Natural calcium derived from pristine, tropical oceans.