Crustose Coralline Alga

Care Summary

Crustose Coralline Algae (CCA) is a prized sign of a healthy, well-established reef tank. It forms flat, hard crusts on rockwork and glass in shades of pink, purple, and red. CCA requires stable calcium (400–450 ppm), alkalinity (8–10 dKH), and magnesium to calcify properly. Provide moderate to high lighting; it competes with nuisance algae for space and helps prevent their spread. Avoid scraping it from rocks — treat it as a reef indicator, not a pest.