I have a 250 watt HPS that I use on my two plants (small stealth grow). But the ballast is louder than I'd like, and it creates a faair amount of heat - so I only use the light when I am around to monitor the situation. Otherwise, when I'm out, I use a 150 watt compact flourescent, a much cooler and quieter light source. The flouro is fine, and the plants are great, but of course the HPS is better... My question: is it stressful to plants to have their light source/quality changed all the time? Am I better off just keeping the flouro as the sole light?