This is hilarious, and wrong.
A lumen is a measure of the visible light for the human eye, which has nothing to do with the wavelength that corals require for photosynthesis.
Corals require PAR, photosynthetic active radiation. You get a better PAR rating with bulbs rated in the 15,000 kelvin. Corals arent plants, they use a different light spectrum to make their food. Which is why you need to replace your bulbs after a year, the spectrum of light the bulbs puts out shifts to a wavelength that is more suitable for algae growth.
But you are right, some people do add in "blue" or "purple" bulbs to change the colors seen in the tank, because the 15,000 kelvin bulb is very yellow, which makes for boring coral colors.
Also watts per gallon/liter is used because its a rule of thumb trick for evaluating T5 and metal halide setups. Very few people have a PAR meter to test this and it would be difficult to publish PAR reading for a fixture because it changes with depth and how high the lights are placed above the tank. LED are changing this rule of thumb, but Im sure in time we will have rule of thumb for evaluating LEDs as well.
Finally, if those $2 lights actually worked to grow corals, dont you think that all of us would be using them? They dont work, they are made to light a room for human eyes, but not to grow corals. You can't even grow land plants under those lights. Which is probably why your nem is dying, you arent providing it with any lighting, and you stuck it into a tank that is totally unable to provide for it.
