your question is which would run hotter. correct?

well from what i had gathered (with no expereince of my own) is that a HPS seems to run steady at about 100 lm/W ( lumens per watt) where as the MH ranges anywhere from 65-115 lm/W.

so i would assume (and we both know what can happen here) is that the electricity that is not getting turned into light is getting turned into heat. so depending on how efficient your MH is will depend on which will run hotter.

i wasn't try to tell you which had more lumens, i was just using the chart as a reference to back my hypothesis.

i guess sometimes i just get so excited to help and instead of chiming in i should just sit back and learn.

and keep the ballast outside the room if possible.

hopefully someone will chime in with experience.


-shake