How close and for how many hours should I run a plant light over 9 plants?

take a look at this  http://extension.missouri.edu/p/G6515

Hi Romablue,
I keep the lights on for 17 hours a day.
The distance depends of your light and the heat it produces...

If you use the T8 lights I mentioned you can keep them 3-4" from the leaves.  You can leave the lights on 10 - 24 hrs/day.  The longer you leave them on the faster they grow and the more often you have to water.  You have to ask yourself if you can handle a lot of growth.  As the leaves start shading each other you'll start needing side lighting.  That can come from 100 W equivalent CFLs.

Thanks for your help, Bob are you talking about these?:
http://www.homedepot.com/p/Philips-4-ft-T8-32-Watt-Plant-and-Aquarium-Linear-Fluorescent-Light-Bulb-429167/203865702?N=5yc1vZc5sh

More like these 2 packs

6500K
http://www.homedepot.com/p/Philips-4-ft-T8-32-Watt-Daylight-Deluxe-6500K-Linear-Fluorescent-ALTO-II-Light-Bulb-2-Pack-422963/203466587

5000K
http://www.homedepot.com/p/Philips-4-ft-T8-32-Watt-Natural-Light-5000K-ALTO-Linear-Fluorescent-Light-Bulb-2-Pack-409664/100613779

3000K
http://www.homedepot.com/p/Philips-4-ft-T8-32-Watt-Soft-White-3000K-Linear-Fluorescent-Light-Bulb-2-Pack-226829/100476639

The prices have gone way up since I bought them so you may want to shop around.