does anyone know how to care for this stuff. im clueless. does it require high light? co2? i bought shrimp off a guy and he gave me some riccia and moss. the riccia was just little tiny pieces but i don't really know what to do with it. right now its floating in my tank but gets covered by the duckweed and kind of obstructed by frogbits. some of the little pieces have gone from light green to dark green so im not sure if its dying or not. suggestions?