I have a 1000 watt HPS bulb and ballast. The grow space I'd like to use is only large enough for a 4-600 watt bulb. Is my ballast most likely made for only 1000 watt bulbs, or will it work fine with a 4-600 watt bulb?
Only for 1000w bulbs. Just make sure you have adequate ventilation (the entire room at least once per minute) and that your intake temperature doesn't exceed 70 degrees. It'll be alright.