Is it possible to grow HC in a 10 gallon tank with only a single 15w fluorescent bulb? The fixture has a white reflector. I was thinking about buying a new light fixture with higher wattage, is it necessary?
It is unlikely that you can do at all well with anything but mosses and other low light plants with so little light. If you visit 13watt Bright Kits and buy two 13 watt retrofit kits, you can grow almost all plants in a ten gallon tank, with good fertilizing and CO2 supply.