Dburr is correct, those lights in h. de pot are not the right spectrum. They are about 4000k. You can get the right ballast from electrical supply houses. Just call and ask if they carry Metal halide ballasts. Tell them what wattage (175, 250, or 400 watt). I bought a 400 watt MH ballast at a local electrical supply house for $66. You will still have to buy the bulb from a mail order aquarium store. I got the Iwasaki 6500k lamp ($59 for the 400 watt lamp). I plan to use VHO actinics with mine. If you don't want to have other lights, get a 10,000k lamp. They are more expensive, but you don't need actinic lights as a supplement. Good luck.
Sonny