Macroalgae export nutrients from reef systems. Top species: Chaetomorpha (chaeto - the standard refugium algae, ball-of-yarn shape, fast nitrate uptake, won't spread), Gracilaria (red feather, edible by tangs), Caulerpa prolifera (fast growing but goes "sexual" + crashes - controversial), Halimeda (calcifying display algae - decorative, slower nutrient export), Ulva (sea lettuce, tang food). Refugium setup: chaeto under 23W LED on reverse photoperiod (when display lights off, refugium on - stabilizes pH overnight). Tumble chaeto with gentle flow to prevent dead pockets. Harvest 30-50% every 2-4 weeks. Display use: Halimeda + red gracilaria can scape into the display tank itself for tang grazing. Caveat: some hobbyists avoid Caulerpa due to "going sexual" (releasing gametes, dying off, polluting tank). Chaeto + Gracilaria are safer.
Reviewed by the Fast Aquatics husbandry team · Updated May 2026
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