Heat generation and lighting choice

[Mikro402]

I have been reading alot about T5 and MH lighting. One thing I'm trying to figure out is how much heat will be generated between the different choices. I definitely want to have either T5HO or MH.
So is heat much higher with MH than T5 or are they close?
(I am trying to avoid buying a chiller. )
How about bulb life and power usage?

I have a 75 gal. 48 X 18D X 20H tank.
The tank is in the basement so it stays around 72 year round.
I have been looking at the AquaticLife 6 X 54W Lamp T5HO, and the Current USA Outer
Orbit 2x250W 10,000K HQI with 4 X 54W T5 HO & 18 Lunar Lights

[FoMoCo Master Tech]

MH produces much more heat and the bulbs have a shorter life span. I'd guess the temperature differential between the two fixtures you listed would be significant.
I believe MH bulbs last around 9 months and T5 last longer than 18 months ( if not overdriven). The benefits from MH are best suited for larger, taller tanks (IMO). T5 bulbs use less power.
I have a 75g with those dimensions as well and I believe you can keep just about any photosynthetic livestock with a 6x54 T5 fixture.
One of the things you won't get much of with t5's is the shimmer effect. The tanks temp will rise with T5's but should be much more manageable than with MH.
Right now, I have my 6x54 fixture surrounded by a canopy with no fans (in the canopy or in the fixture) and my temp only climbs 1 degree or so. The summer heat will force me to put fans in the canopy but I doubt I'll need a chiller. Hope this helps.

[reeferbill]

Hi Mikro402 : Have you checked out the new LEDs their prices are starting to come down and you could build one? Right now I am using Metal Halide because I ruined my Nova Exteme Pro T-5 6@39 watt fixture running it without a cover. It only lasted about 10 months and they refused to honor 1 year warranty when they looked at how corroded it had gotten from the saltwater. I think I get better growth rates on my corals with the metal halide and I like the shimmer. The t-5s run cooler though and you can always add a LED stunner strip to add some shimmer. Happy Reefing!!!!!!!!!!!!