400w metal halide and 400w high pressure sodium bulbs.

It would be good to have both running for a fuller spectrum and higher wattage of light. You would be almost at 800 with both lamps burning at the same time. It would double your electrical consumption though and it sounds like you are concerned with that. Another issue with 800 watts of light is heat. You would have to figure out how to cool your space.

Iff you can cool your space with two lamps, you can phase the lights. Fire the HPS and run it for a couple of hours before firing the MH. Let the two lamps run for 8 hours together and then cut the MH a couple of hours before your 12. The MH is less efficient than the HPS. You would limit your cost of running the multiple lamps and gain the benefit of the extra lighting. Hope that makes sense.

im jus gna runn both for this month and see how much the bill is and i can get an idea of wat im gna b payn..
thnx for that idea tho i may use it

it stays under 80 degrees with both lamps on

my plants under the 400w mh seem to be doin better than the ones under 400w hps y is that.? should i change it to a mh bulb

im running a 800w setup by the way