Scientific name: Chaetomorpha sp. Common Names: Chaeto, Spaghetti Algae, Green Hair Algae, Brillo Pad Algae Geographic Origin: Ubiquitous in tropical seas; aquacultured Type: Filamentous macroalgae Maximum size: Grows into a clump, size dependent on how much it is allowed to grow Lighting Required: moderate to high, 13,000 - 16,000 Lux, 10-12 hours/day Temperature: 72-82 F, stability more important than exact temp Water Chemistry: pH 8.0 - 8.3, temps 72-83 and stable, s.g. 1.023-1.025, Ca2+ 400ppm Growth rates: Relatively rapid Demands: Moderate Care: Chaetomorpha is a green macroalgae from the Division Chlorophyta and is one of the more common plants to keep in your marine aquarium to help maintain your water purity. The most common species is Chaetomorpha linum and is probably what is in your tank. Other species include Chaetomorpha cannibina and antennina. Under the right conditions, this macro can virtually 'vacuum' your aquarium clean of nitrates and phosphates. Chaeto is generally kept in a refugium under moderate to high lighting and grows into a large fuzzy ball. It does best with good water flow, and, in some refugiums, will need to be 'de-bulked' over time. In so doing, this reduces the mass of chaeto as it enlarges, ridding it of accumulated debris. You may even have to rinse it in aquarium water like a sponge. This is probably the most important task you will have to do to it to maintain it's health. When aquacultured, chaeto is usually tumbled, however, in moderate to high water flow, it should do fine. This plant is a macroalgae and grows in filamentous strands. Each individual cell is tubular in shape. Although it can be placed in the main aquarium, active growth may make it a nuisance and is best kept in the refugium. Chaeto should be illuminated 'opposite the main aquarium', i.e., when the aquarium lights go off, the refugium light goes on. This helps to reduce the nightly pH swings that can occur in our marine reef aquariums. In general, most reefers will illuminate for 10-12 hours per day. Chaeto is my favorite as a nutrient exporter and one of the reasons I prefer it is that it will not 'go sexual' like Caulerpa and release nutrients and reproductive products back into the water column. Nothing is written in stone though and many green algaes have this ability. Of note, there aren't many natural predators of chaeto, so, you'll have to prune it. Although they will scrub your water column of phospate and nitrates, elevated levels of these can be harmful.