Have you read this part in a thread elsewhere?
Beyond choosing lighting that is optimal for photosynthesis, as above, you should choose lighting with the color temperature that best suits the aesthetic goals of your tank. So, don't obsess about color temperature beyond how you want your tank to look. From a color temperature standpoint, blue-colored light will enhance blues in your fish. Green-colored light will make the tank look bright to humans and enhance the green color of your plants. Red-colored light will enhance the reds in your fish, and any red plants.
Lux is lumens/square meter, so they are similar. They are both defined in terms that are meaningful to human perception of light – not plants. They stress the amount of energy in the green band to which humans are most sensitive – not plants.
Artificial light sources are usually evaluated based on their lumen output. Lumen is a measure of flux, or how much light energy a light source emits (per unit time). The lumen measure does not include all the energy the source emits, but just the energy with wavelengths capable of affecting the human eye. Thus the lumen measure is defined in such a way as to be weighted by the (bright-adapted) human eye spectral sensitivity.
Lumen ratings are usually available, but when you use them you have to keep in mind what they mean. Lamp A can have a higher lumen rating than lamp B and appear brighter to you, while lamp B provides more useful light for plants. Compare the lumen ratings for cool white and GroLux bulbs of the same wattage and you will see what I mean. A 40-watt cool white bulb is rated at 3050 lumen; a 40-watt GroLux bulb (not the wide spectrum) is way lower at 1200 lumens. The big difference is because GroLux lamps provide very little green light and cool whites provide a lot of green light. I have found it best to provide a mix of lighting to a planted tank. The GroLux bulb is perhaps the best plant bulb available but it has very little green light so the visual effects of your tank will look dim and purplish. Yet if you add some other lighting such as a Philips 6500K the effect is more pleasing to the eye and still beneficial to the plants. I find that the GroLux along with a GroLux wide spectrum (89 Color Rendering Index) has a great effect for use as dawn/dusk lighting. (A Sylvania rep. told me it was best to use both together.)
Kelvin rating and lumens does not equate for plants. The Kelvin scale is more of how your tank will look to you/us and is totally subjective. It is true that the lower Kelvin ratings like 3000K will have more red light and a 10,000K will have more blue light. Lumens are meaningless for plants, as green plants do not utilize green light for photosynthesis. A higher lumen rating at the same wattage often means greener light. Lumen is a rating weighted entirely towards human perception. It has little to do with the value of a light for either growing or viewing plants.