Need more heat

I'm having trouble keeping my box warm enough. It's in an area that can get down to 50 F. I have a 400 wt MH with an air cooled reflector and the box vented with a 6" voertex fan... I put a little heater in the 4x4x4 box - but it can't get the temp up enough (70-75F) -- I'm thinking of unplugging my light cooling fan - to get heat from the light? Thanks for some ideas...

yes that is the easiest way to add heat. remove your venting from your light and just use the hood. ur temps will go up by about 10*