I have a 16 gal tank with 4 dwarf puffers in it. It's planted with anubias and a moss ball (the moss ball stays at the bottom and doesn't move much unless I turn it). I've been noticing that it's starting to look a little brownish. I've been keeping the lights on 6-10 hours/day. I have some liquid plant food that I add irregularly. (Maybe once or twice/week). Not enough food or could I be doing something else wrong? I have 4 dwarf puffers in the tank.