Can I used double ended Metal Halide lamps in my Pro 1000W fixture?

No. Our Pro-line fixtures and ballasts have been specifically developed to drive HPS lamps. Using a MH lamp in a high frequency HPS ballast can be very dangerous, as the HPS ballasts do not have a timer that prevents hot re-strike. MH lamps need to cool down 10 minutes before they are ignited again.

Secondly, in an open reflector you should always use lamps that are rated for open reflectors. HPS lamps are suitable for open reflectors, very few MH lamps are. Metal Halide lamps work on a much higher pressure than HPS lamps, and when they fail they fail explosive, taking with them the outer balloon. 

Thirdly, our fixtures are specifically developed for non-ANSI double ended high frequency HPS lamps, and approved for this use by CSA and/or UL. Using a wrong lamp in it is unintended use. It not only voids your Gavita warranty, but if for any reason a fire might break out because of such a lamp breaking, your insurance will not cover it. 

Protected Metal Halide lamps have a special extra cover around the arc tube to prevent the outer balloon from failing when the arc tube fails. They carry a ANSI /O rating, meaning that they are suitable for open fixtures. The Double Ended MH lamps that we know of do not have a /O rating.