Macroalgae

Macroalgae are large, photosynthetic marine algae used in reef tanks for both aesthetics and nutrient control. They fall into three main groups:

  • Red Algae — Rhodophyta
    Often deeper-colored (reds, purples) and can thrive in lower light. Includes decorative species and coralline algae.
  • Green Algae — Chlorophyta
    Bright green, fast-growing, and highly efficient at absorbing nutrients. Typically require stronger lighting.
  • Brown Algae — Phaeophyceae
    Ranges from soft, bushy forms to tougher, structured species. Generally prefer stable conditions and moderate nutrients.

Care Guidelines

  • Lighting: Moderate to high depending on species (greens usually need the most, reds the least)
  • Flow: Moderate flow to keep surfaces clean and promote growth
  • Nutrients: Require available nitrate and phosphate; ultra-low nutrient tanks will not support growth
  • Temperature: 75–81°F
  • Salinity: 1.024–1.026

Key Notes

  • Macroalgae actively remove nutrients from the water, helping stabilize your system
  • Growth rate varies... some species are controlled and ornamental, others can spread quickly
  • Regular trimming is often required to maintain balance