Coralline algae mark a mature reef tank. Color range: pink, purple, red, orange, green, occasionally white. Different species look distinct. Growth requirements: stable alkalinity (8-10 dKH), calcium 400-450 ppm, magnesium 1280-1450 ppm, low phosphate (under 0.1 ppm), strong flow. Light: medium-PAR blue spectrum (which is why corals + coralline grow better under blue-heavy reef LEDs). How to encourage: 1) stable parameters (the most important factor). 2) clean rock with a brush + magnet to remove film algae - coralline competes for surface. 3) seed by adding established live rock or coralline-encrusted frag plug. 4) magnesium 1300+ helps coralline outcompete green/brown algae. Removal from glass: credit card or razor blade. Magnetic algae cleaners can't cut it. Significance: a tank fully encrusted in coralline within 6-12 months indicates rock-solid water chemistry.
Reviewed by the Fast Aquatics husbandry team · Updated May 2026
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