I have these rapid growing plants that i got from my friend. In his tank they are a nice light green but in my tank they turn all brown and horrible like theres something growing on them. When a new part of the plant grows it is a light green at first but then it turns that mankey brown. http://pic80.picturetrail.com/VOL2124/10185440/18306454/288327065.jpg
heres a pic (i Hope) can you tell what species of plant this is and how I can stop it from going manky brown