I have a sun system 250 watt grow light I bought from a freind (50.00) he said that it can be converted to a higher watt system but I can't find any info on this. Can it be done.
strike that I think I want a 600 watt system
You can almost certainly use the reflector with the higher powered lamp but you will need a new, or rather different, ballast. The wattage of the ballast has to match the lamp wattage and it must be appropriate to the lamp type (metal halide or high pressure sodium.) Sounds like you're talking about HPS since I've never seen a 600W MH lamp or ballast.