Refugium macroalgae
Marine algae grown in the refugium to absorb nitrates and phosphates naturally. A biological alternative to chemical filters.
Detailed explanation
The macroalgae in the refugium are the most effective natural filter for a marine aquarium. As they grow they absorb nitrates, phosphates and other nutrients from the water, directly competing with unwanted algae in the display.
Chaetomorpha is the most popular macroalgae for refugium. It grows like a tangled mass of green filaments. It does not stick to rocks, is easy to thin out and does not release spores into the aquarium. Requires moderate light (80-100 PAR) for a photoperiod inverse to the display (on at night when the display is off).
Caulerpa is very effective in absorbing nutrients but can undergo sexual reproduction (sporulation), releasing millions of gametes which clog the water making it milky green. To avoid this, it is kept under continuous lighting 24 hours a day and pruned regularly.
Gracilaria (ogo) is an excellent red algae. It grows well, absorbs nutrients and the Tang eat it willingly. It can serve both as a filter and as food for herbivorous fish.
Other options include Ulva (sea lettuce) and Halimeda (limestone algae that also consumes calcium and KH).
The refugium with macroalgae works best when: it has its own specific spectrum LED (vegetable growth), it has a moderate water flow, it is thinned regularly by removing excess algae (and with it the absorbed nutrients).
Reverse lighting (macroalgae turned on at night) stabilises the pH of the entire aquarium. When the display lights go off the pH would tend to drop due to the corals' respiration. The illuminated macroalgae in the refugium continue photosynthesis and compensate for CO2 production.
Coralia Lab monitors this parameter with AI diagnostics. Tank Score alerts you when a value moves outside the recommended range for your aquarium.
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