how much light?

[killitex]

I have a 110 gallon tank that I would like to have as a planted tank. How many watts per gallon do I need to grow a heavy amount of plants? Which kind of light and fixture do you recommend? Do I need CO2?

[mnemenoi]

I have always heard the 2-3 watts per gallon rule, so going by that I'd recommend a system that offered 220 watts (low end) and 330 (higher end). With the larger plant load it sounds like the higher end would be preferred. As far as spectrum goes I would shoot for something between 6500K and 12,000 K. You will likely want to play around with some differing bulbs to determine the right look and feel for your specific tastes. I myself enjoy a 12,000k bulb teamed with a 7500K, but I'm certain each person has their own tastes. Co2 is useful in growing certain plants and helping guard against algae outbreaks. I myself do not use it, but many do on here. As far as fixtures go, I would look at features you want. Many come with timers, moonlight LED's, and different combination of controls. Looking over what is available you could reasonably go with a 4 - 6 bulb T-5 system or perhaps consider a MH combination. The real concern with MH is not having an even distribution and heat.