Plants 3 days under a 250w mh, lightening to more yellow, is this normal?

I'm new to growin and all 5 of my plants have been a deep green under 355w of cfl for the last 3 weeks, i just recently got a 250w mh/hps and 3 days under the new light the plants seem to be yellowing lightening up in color, is this normal?

the light is 7 inches away from them as well but temp doesent get higher than 80

No, I use a 250W MH from the start. The plant might have to do more work (if it got more intense light), and as such require different watering/feeding, but they should not yellow.

sounds like they bleaching a little from too much light... raise the lights to about 20 inches and see if they recover