Benzelsanswered grow question 3 years ago If it has a brightness control knob on it or you have a digital controller then some people swear by running the new more powerful light at 75-80% for a few days to a week and then turning it up to 100% just to ease them into the brighter light, but its not like your going from 100W to 350W or more.
150W to 250W will be fine even at full power. They will love it and you will never go back to the 150W. Also If your running 150W Fluros like your diary says- look into A LED light in the 100W range- it will throw more light then the 250W fluros easily with much less heat.