I love my LED's I switched because I was sick of buying new T5 bulbs every year, so if all I save is the $200 a year (bulb replacement) then so be it.

"This change of phase (from a liquid to a gas) requires heat, called "latent heat". When water evaporates, it removes heat, lowering the temperature of whatever the water was in contact with. For both water and land surface, most of this heat energy comes from the surface, not from the air. "

Ref: http://www.weatherquestions.com/What_is_evaporation.htm

OK, I just noticed a huge flaw in my numbers. The 0.84 kWh per day for the mitras is only one fixture. See correction below:

Executive Summary:
LED power used: 2.52 kWh per day
Metal Halide Comparison: 6.12 kWh per day
Heater power saved from Halides: 0.91 kWh per day
LED power savings: 2.69 kWh per day
In this case the power saved with LEDs is still substantial including the extra power requirement from heaters.

Some system details
Display tank volume: 270 gallons
Connected frag tank and sump volume: 70 gallons
Realistic water volume approximation: 300 gallons.
Maintained water temperature: 78F
Lights: 3 x Mitra
Heaters: 2 x 300W

Insulation and equipment heat addition:
15mm glass with only view-able side but has an open top.
Sumps are acrylic and contained in a humidity controlled room which stays fairly humid and warm meaning heat loss from the sumps will be minor.
I'll installed all my pumps internal to take advantage of their heat loss.
I also have fridges under the main tank which vent around the sides and back.
In other words I've taken some steps to add as much heat to the tank from equipment and keep it in as much as possible without doing something that would have negative effects. I mention this because I think it's important when looking at your own tank you consider how heat loss/addition will effect your savings.

Measured Results:
Lights run for 12 hours, peak at 135W dimming up and down. Power used per fixture per day is 0.84 kWh, total for all three fixtures 2.52 kWh per day.
I measured the power used by the heaters a few different ways, during the full 12 hours on different days, during the peak light time and 24-7 to get a feel for any changes in usage that occur. I concluded the heaters duty cycle doesn't fluctuate substantially and they use an average of 0.13 kW per hour.

Now for the debatable part, the comparison.
The mitras run in high output mode, GHL claims it's comparable to 340W of halide, however I would no way compare the 12 hours of ramping up and down to that of a solid state 340W halide. Rather I believe it's comparable to 6 hours of equivalent halide which is 6.12 kWh per day excluding any inefficiencies.
In my experience when halides are on, heaters are off. I also think another hour is fair for a cooling off period. In other words I'm assuming the halides save me 7 hours of heat which is 0.91 kWh per day.

Conclusion
LEDs save me money in electricity even with heating cost included. A total savings of 2.69 kWh per day or approximately 44% decrease. However I believe the steps I've taken to with hold heat are a key player for this savings, I've noticed the heaters activate much less frequently from switching to acrylic sumps alone. I also maintain my temp at 78F while many SPS gurus will keep it closer to 80F which could play a role as well. This of course was also a winter reading, results will be different if house temperature climbs during hot summer days. Other peoples results will vary but the substantial difference I measured should conclude in virtually all cases the electricity savings are real.

LEDs and electricity savings
 

My fish told me they would run away if I took away their Mitras. And take their corals with them!

I have lots of other reasons to use LEDs but the main one for me is the ramping up and down and color choice, so much more realistic than the on / off of other lighting options. I spend tons of time and money trying to duplicate the ocean, the sun is just part of it.

Thanks for the numbers Steve!

I may have missed something (not reading all the led's are great or garbage) but when did Mrhasan turn from the biggest led fan to having to debate how crappy they are in led threads.

-On to the original topic I have noticed the power savings just by looking at my power bills over the last couple years. My bill is down compared to when I ran my 90gal with MH over it vs the 225 I'm running with 2 massive return pumps (albeit dc) a huge increase in skimmer and the 4 mp40's I run now instead of 2 mp10's. I didn't go into full research mode like Steven did (he's way smarter than I am) but looking over my power bills for a similar 6 month period comparing the 2 setups.

Will the savings pay for my 3 Mitras? No bloody way lol (not in my lifetime considering all the money I lost trying all the other fixtures :twised:) That being said I would ever go back to T5 or halides.

There is nothing in this hobby that will save you money outside of shutting down and staring at the blank wall where your tank used to sit.

Even that doesn't work out so well, I'm sure Brett will agree :surprise:

lol only works if you never come back :mrgreen:

Although the build is of my favorite parts......maybe when I move again lol

i just got bitch slapped right through a wall :lol:

Steve ain't holding nuthin back today. Let's go sit in a corner and cry together. :cry: