Lights that would work with canopy

While the Kessils are excellent, I would definitely consider the AquaRay.

The 600, 1500, & 2000 tiles easily screw into a canopy without any additional parts

These also produce much less excess heat than other brands, in part because they utilize PWM technology, which most others do not.

The AquRay also have a much higher output of PAR per watt of energy consumed, requiring a much lower amount of wattage.
Their warranty is also by far the best with 5 years compared to 1-2 years for all others.
Reference:
http://aquariumopinions.com/2013/12/16/aquarium-led-warranties-reef-or-planted/
http://aquariumopinions.com/2013/07/07/aquarium-led-lights-controllers-what-is-best/

Here are a few other good reads/references with further information to back up why I prefer the AquaRay :
http://aquarium-digest.com/2010/04/11/led-aquarium-lights-lighting/
http://aap.atrixnet.com/?p=338

As long as your canopy isn't ultra low-profile, you should be fine with any of the better fixtures out there as long as you allow several inches between the top of the fixture and the underside of your canopy top. FWIW, I don't think there is a cooler running LED than Kessil. No built in controller so you would need to add one if you want that ability. I don't see a major mod being needed for the kessil unless you wanted to drill holes.

I have to respectfully disagree as to the Kessil being the coolest running LED.
The fact that these require a cooling fan and lack PWM is show why these are a hotter running LED.

As well, as my the first reference points out, the Kessil only has a 1 year warranty, and in my opinion, that is in part due to a shorter life span because of the fan

I'll give you that but mine are cooler to the touch than any (3W +) LED fixture I have seen/touched. The fact that the fan is virtually dead silent is also a plus.

I found this new LED Comparison Chart very helpful/interesting:

http://aquarium-digest.com/2014/01/...-choosing-your-aquarium-lights/#ledcomparison

The article as a whole was a good read, but it was the chart at the end that really caught my attention

The Taotronics definitely has one of the best start up costs and initial "bang for your buck"

My problem with these is long term costs, and not just electrical usage, more so replacement 2 or 3 years later since fan burn out and failure can and does happen with these.
But admittedly you have to suffer at least one failure AND combine the higher operating cost for the Taotronics to not be the best price.
That said, with my aquarium service business, if I sell a customer a product that later fails and they find I could have sold them a better product, I would have one angry service customer :angryfire:

Ummm, DIY! But seriously, that article was funny. I stopped at that BS about 'current reduction' vs 'pwm' because anyone that knows anything about LEDs knows that PWM is MUCH more damaging to LEDs because you are constantly turning them off/on to create the desired brightness, it just turns off many times a second so our eyes don't notice the flicker. LEDs have the same faults as an incandescent bulb in that respect, you can only turn them off/on so many times before they fry, where as running them at a lower current but within proper forward voltage via 10v manual dimming will not cause excess heat or damage to a properly built LED fixture, key word, properly. The only way a 'current reduction' method would damage LEDs is it you are using the wrong drivers (constant voltage instead of constant current) or very mismatched LEDs. LEDs are actually MORE efficient running in the 500-700mA current range than they are running at full current (1000mA-1500mA), the lumens per watt is much higher at the lower currents. If one uses cheap chinese LEDs that have a wide range of specifications for forward voltages and you put them all in the same series of LEDs, some of them will be driven slightly harder than they should be. Easy solution, always use quality LEDs (Cree, OSRAM, Philips), and always use quality drivers (Meanwell). On top of that, always by the same BIN LEDs and put those in the same series, so one 'channel' is all cool whites, one is all royal blues, one is violet, one is cyan, one is red, etc, that way you will never run into the problem described in the article regarding mismatched LEDs.

Kessils are fantastic lights, but I would never recommend them for a 6' tank. You would need a few dozen to cover a 6' tank adequately.

As for cost, here's one for you. I spent $1000 building 2 LED fixtures 6 years ago, one for my 60G, one for my 75G, in those 6 years I have had maybe 6 LEDs burn out and need replacement, and since it was DIY, it took me all of 60 seconds to replace and $3ea for the LEDs, FAR FAR cheaper than having to replace T5s or MH. In those 6 years, if I add up bulb replacement cost that I was spending annually ($320), plus electricity savings $28,000+ in 6 years, it really is a no brainer which lighting technology is superior.

Today the light I made for my 60G that cost about $400 6 years ago can be made for under $150, and use much more efficient LEDs than I am using (Cree XR-E). I have never had a fan go bad, but I made sure to buy the correct type for mounting horizontal, spent $20 per fan, but if one did die, $20 for a fan from newegg and 2 minutes of work to replace it. The fans are dead quite, loudest part of my tank is the slight gurgling on the overflow pipe. On my 75G light I have my fans on a PWM controller with the LEDs, and on a temp controller, so the fans are either off or spin very slowly (140mm fans) when the temp of the heatsink exceeds 90f, well below operating specs of the LEDs. Money I have spent replacing blown LEDs over 6 years, ~$20, less than the price of 1 T5 bulb.

Ace25.
I will have to agree to respectfully disagree, as I & others I know have been using LEDs powered by PWM for almost 5 years and not had any damage (the warranty speaks for itself), so sorry the article is not laughable, nor are others that I have read backing this up
I also have a friend who knows a lot more on the subject who also backed this up to me

Interestingly, it is the lights of the same brand running with the controllers that have had less issues requiring warranty replacement than those just running with a power supply, not that there have been too many issues

As for heat, this is another aspect I have noted and that is the excess heat production of many LED fixtures, thus requiring a fan. Access heat equals energy lost that is simply not going to light energy.