I agree with going with a Lumatek ballast. You can get a Lumatek 400 Watt HPS/MH ballast that is dimmable to 250watt and I think there is a setting in between that is like 360 or 370 watts and there is also a super lumens setting. They have 400/600 watt model also. Lumatek is definitely considered one of the best if not the best ballasts out there and there warranty is great as mentioned by Rancho.If you go with lower end products like ipower be sure to find out warranty info from store and manufacturer. With Lumatek you are guarenteed a replacement ballast if it fails within 5 years and with Digilux you are guarenteed a replacement bulb if it fails within 12 months. Free replacement free shipping.