Difference between 2.6 and 2.27 watts/gal?

[beviking]

I'm adding two more lights (Normal Fluorescent) to my 90g tank for a total of 6 lights. I like the T8 34Watt bulbs but am wondering if T12 40Watt bulbs would be more beneficial (allow greater variety of plants) or is the difference negligible?

[DIYMatt]

I would say the difference would neglible. The T8's have some advantages to the T12's that might even make them superior to the T12's. Assuming you have the same bulb, etc.

[Captain Hook]

I've heard that T8 bulbs provide more light than T12s. It has something to do with less surface area of light or something.