We sell both C. mexicana (wide blade) and C. sertulariodes (fine blade) caleurpas. If you have a preference, please let us know prior to ordering. Both do well in a refugium type setting. It can be used in a display tank, but it's easier to control in cull in a refugium. Good at reducing nitrates and phospates, and some fish, especially tangs will nibble on it. Sold in an 8" bag, roughly 8 oz dry weight