....that, if you're using flourescents, you need as much as you can find. I sprouted some seedlings and put them under 2 4 ft. T8 38 Watt 4100K tubes-about 2 inches above. My plants were stretching so hard for the light, they were about to topple over from being so lanky and thin.
I repotted them up to the first leaves as someone on here suggested and put them under a 400 W Metal Halide and they're flourishing. Point is, I don't think you'll be able to leave them under your current flourescent lights too long or they won't grow right. Friend is right, though. The spectrum and Kelvin temp are the things. I just realized you're talking about T12 bulbs at 70 watts, so I'm not really sure.
As a side note, I'm going to try more seedlings under my flourescent fixture, but I just got 2 tubes rated DAYLIGHT with a 6500K rating. I'll keep you posted.
AG