I've been looking at lighting and would like to go with LED for a number of reasons, none of which have much to do with how good they are for the tank overall.
Marineland single bright over the double bright, due mainly to cost (double is over three times the cost) and the impression that a whole bunch of lights are likely better than not so many... did I mention that they are 1/3 the price?
Long bulb life, compact design, low power consumption, low heat production, cool lighting effects.
The light spectrum chart looks decent so I would assume (??) that it is OK for plant growth. I think it peaks at 6,000K.
Comparing only the three fixtures (18" size and 17" strip) the LUX ratings are wildly different.
Double = 3500LUX at 12" and 1550LUX at 24"... I assume that these are in air, not water... adjust accordingly.
Single = 790LUX at 12" and 250 at 24" that's quite a reduction, 68% loss at 24" compared to 56% with the double.
Strip - 886LUX at 12" and 302 at 24". but it's a linear strip as opposed to a wide coverage.
I don't know why they called it the double, there are over 8 times the lights, 4 times the LUX, 66% more wattage
I would expect that low light plants are in order and I also expect that, seeing as my tank will be 24", that I should go up to the 24"-36" unit rather than the 18"-24" for the 20% gain in LUX.
It's cheaper to go with two units than the double bright if needed... overhead and a strip light perhaps. Two could work into some better timed light level controls as well.
Perhaps I am over thinking this too.