400w MH to 250w MH - Big temperature difference?

[Todd]

So, I have been finding I don't really need to be running 400w MH over my tank, and since I got a call from the landlord curious about the high power usage, I figure now would be a good time to change to 250 w MH.

Part of my logic behind this is that the 250w bulbs should run cooler - is this correct? Having almost 1000w of light in my canopy over a 135g tank means that it is hot, particularly with this mini heat wave we have been having in Victoria. I find that the profilux turns the MH off really quickly as the tank heats up.

Will there be a significant difference in the bulb temperature between the 400w MH and 250w MH? I know I will see a difference on the ballast end (moving from an old magnetic ballast to digital).

Also does anyone have any feedback on the lumatek ballasts? I am thinking of getting two of those. I have 20 000 K XM SE bulbs right now, any recommendations for 250w bulbs?