If your ballast is for 250 watts, then good to go, sunpod 250s have external ballasts. If yours is a 150 watt George, it will have an internal ballast and not work with these.
George, not sure how your sunpod is set up, but if you are running 150s now, you will need to change out the ballast for a 250w ballast, you can't just change out the bulbs...