My moss grows fine and spreads like fire, but everything else's leaves go thin and yello, or brown at the tips and die off, but they new leaves just keep p enough to keep the plants going, if rather badly. I dose with flourish trace and some freeby ferts i have, lighing is 18w over 35l but all plants are fairly low lighting. inert substrate. oh and for wome reason hc grows like mad in this tank? any ideas on what is happening?