Hello! I need help. I have a 55 gallon tank that's lightly planted with vallisneria swords and another plant. :\ I left on a trip for 5 days and I asked my sister to turn the lights on and off (the timer broke) and she didn't. ThAt might not be the cause of tue problem, but my water is green. Can you help me? There are no fish and the tank is 2 months old.