Mermaids fan is a calcified member of the Udotea family, and is a green macroalgae. It can be used for filtration, but is best suited for the display tank because of its great potential in aquascaping. It is highly calcified and will not be eaten by fish or snails, making it ideal as a display piece. It dooes best when planted in a fine sandy substrate, but can survive in more coarse substrates as well. Despite its slower growth rate it will get some filtering done if placed in your display tank, or in your display sump.
This algae is capable of living under low-moderate light, it will grow strongest in moderate to high lighting. All macros present some risk of going sexual and releasing carbon dioxide into you aqaurium. However, the risk of adverse ph changes from the release of carbon from this species is extremely low. Because this plant uses calcium to grow, you should keep your tank within 350-450 ppm of calcium for best results.