Chaeto macroalgae (Chaetomorpha linum) is the standard refugium algae for fast, dependable nutrient export. Its wiry green strands use nitrate and phosphate, stay free from rockwork, and form a dense refuge for copepods, amphipods, and mysid shrimp. Unlike many attached or runner-forming algae, Chaetomorpha remains a loose mass that is simple to harvest. Chaeto macroalgae quick care facts Scientific name Chaetomorpha linum Algae group Green filamentous macroalgae Care level Easy Light Moderate to high, full spectrum or refugium grow spectrum Water flow Moderate to high; a slow tumble is ideal Growth rate Fast Best placement Refugium or macroalgae reactor Nutrient export High Food value Low; valued mainly as filtration and pod habitat Portion Golf Ball, Tennis Ball, or Soft Ball Why keep Chaeto macroalgae? Fast growth turns nitrate and phosphate into removable biomass. Does not root into rockwork and has a very low risk of becoming invasive. Dense strands shelter breeding copepods, amphipods, and mysid shrimp. A reverse photoperiod can offset part of the display tank’s overnight pH drop. Lighting, flow, and nutrients Run a dedicated refugium light 12–16 hours per day, often opposite the display lights. Use enough flow to move water through the mass and, when possible, rotate it slowly so every side receives light. The Brightwell ChaetoGro supplies nutrients formulated for Chaeto, but only dose after testing; nitrate and phosphate must remain measurable for growth. Refugium or display tank? Keep Chaeto in a refugium or macroalgae reactor rather than the display. Loose strands can drift into pumps and the wiry mass is not an attractive permanent aquascape. Leave room for the ball to expand without blocking the chamber, and prevent it from pressing against a hot light or pump intake. Harvesting and pruning When the chamber fills or the center begins to shade, remove one-third to one-half of the mass. That physical removal is the nutrient export. Keep the cleanest bright-green portion and pull out dark, soft, or compacted areas. Do not let a large ball become so dense that water cannot pass through it. Troubleshooting Chaeto macroalgae Chaeto that stops growing usually lacks usable light, flow, nitrate, phosphate, or trace iron. A pale outer layer can indicate excessive intensity; a dark, dirty center points to self-shading and detritus. Test before dosing. If nitrate and phosphate are both zero, shorten the refugium photoperiod or reduce the culture before adding supplements. How Chaeto macroalgae compares Chaeto is the strongest all-around refugium choice because it grows quickly without attaching. Red Ogo and Pom Pom Gracilaria also export nutrients and can be fed to herbivores. Sea Lettuce grows fast but can fragment or undergo a reproductive event, so it needs closer harvesting. Portion sizes, shipping, and acclimation Choose a Golf Ball starter amount, a Tennis Ball portion, or a larger Soft Ball portion. Float the sealed bag to equalize temperature, then rinse the algae in discarded aquarium water and inspect it. Start the culture a little farther from the refugium light for several days before increasing intensity. Pairs well with Kessil H80 Tuna Flora or AI Blade Refugium Light for growth, Brightwell ChaetoGro for targeted supplementation, Live Mixed Copepods for habitat seeding, and nitrate/phosphate test kits for control.
