Lights for a planted tank

[yilduz]

So, I don't really have a real fish shop where I live so I was looking in the hardware section of another store for lights. I found the fluorescent lights but some of them didn't have all the information I was looking for. Some of them had the kelvin but some did not. Of those that did, and of those remaining that had a range of somewhere between 6,500 and 10,000, the wattage wasn't what I was expecting. I've read in this forum that low-medium requires about 2-3 watts per gallon (for me, that's 110 to 165 watts) but the bulbs I was finding were around 30 watts, which means I'd need 4 to 5 bulbs and that just seems like a lot. I did notice, though, that they said something like "power input" or something like that for the wattage. Is that the number I should be looking at, or is there a "power output" or something else I should be paying attention to? There was a light output number on most of them, too, but it was measured in lumens. Am I looking at the right stuff and do these lights just kind of suck, or is there something I'm missing?

 

[BigJim]

You will need to inject CO2 if you put your tank in the 2-3 Wpg range. A two-bulb T8 shop light with 40W daylight spectrum bulbs and decent reflectors will be good enough for med-low plants. 48" T8 bulbs come in either 32W or 40W varieties.

Light is a complicated entity. We use Wpg as a rule of thumb because the actual quantities we care about require expensive equipment to measure.