Carib Sea Purple Up 237mlPurpleUp uses a unique dual method approach to coralline algae acceleration. It contains ionic calcium; which immediately raises dissolved calcium levels in your aquarium water. At the same time Super Sea CalciumTM (a 10 micron aragonite powder derived from natural seawater) targets the live rock surface. This dissolves in situ; delivering calcium, strontium, magnesium, and carbonate right where it's needed. PurpleUp also replenishes iodine; an essential element for coralline algae tissues that quickly becomes depleted in closed systems. PurpleUp is not a fertilizer, it does not promote the growth of nuisance algae.