[BigAl07]

One thing to take into consideration Re: PAR - This (in overly simplistic terms) is measuring the light photons striking the sensor. It doesn't measure WHAT type of photon (high in the spectrum, low, etc). So with that being said a MH with say 250 PAR is pretty good but a good portion of that 250 PAR is light that may not be useable by our coral. Look at a spectral graph for MH bulbs and you'll see peaks all over the place (which isn't absolutely bad but not part of this discussion). Now look at LED and see how it's spectral graph is much more defined. So in essence if the LED was putting out the same 250 PAR and it was in the correct spectrum for said coral then it's easy to surmise that more light energy that's useable for our coral is being created by the LED.

Re: Close to the water and heat up the tank for nanos - that's one of the BEAUTIES of LEDs. Their heat isn't projected down into the water from the light source. It comes from the back of the DIODE. Also unless you're using special Infrared LED (which you're not unless you've stuck your TV remote control into the tank) your LED is emitting little to no IR heat. That's why they keep the tank cooler but also why they require a massive heatsink.