I have a 200L tank w/ 2 angels (1big and 1 smaller) 2 bottom feeders, 9 neons and a red-tailed shark. Everybody seems happy in the tank, just one little problem. I have chosen to go the plastic plant route for now, but there is always this brown, sometimes really dark brown agea type growth on the plants. It has at one point gotten out of control and had to throw away all the plants and get new ones and now these have the growth starting again. I have attempted to control this with some Algol and other chem. warfare to no avail. Is there something else I should be looking at? thanks for the help. BTW I have flourescent lighting on for 5 hrs in morning and another 5 in the afternoon with a 2 hr nap time at mid day and they are off all night. I regiously clean the gravel every week with a vacuum and at least a 10% water change. All readings from test kits show all chemicals within normal limits.