CaribSea PurpleUp is a pink and purple coralline algae accelerator. Since PurpleUp is not a fertilizer, it does not promote the growth of nuisance algae. How does it work? PurpleUp 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 Calcium (a 10 micron aragonite powder derived from natural seawater) targets the live rock surface. Super Sea Calcium dissolves 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 an excellent addition to any aquarium with stony corals too!