I recently upgrade my lighting to a metal halide system which has been running for a little over a week now. My question is a few days ago one of the bulbs appears to have a different color than the other. One of the bulb appears to have more of a goldish light while the other seems to be more of a crisp white light. There is a clear color difference between them as the tank is basically divided in half color wise by the two lights. They are 15k and is one of them bad? Being new to these lights any input would be greatly appreciated.