Streptocarpus Dimetris

Is anyone growing under these bulbs? I have some questions regarding what the distance should be from the tops of the plants (or even shelf to light distance) and duration that the lights are on each day. The rack that I'm using seems to be too warm. It has a two bulb setup, 4feet long. and about 14 inches off the tops of the plants. The bulbs in there are grow type lights, one a red spectrum and the other a blue.

I'd appreciate hearing from someone who has had luck with a similar setup.