The K rating actually does effect growth of the plant.
I'm afraid it has very little to nothing to do with plants growth, Kelvin ratings are purely for aesthetic use.
Especially when the intensity of the light is not sufficient.
Kelvin has no sway on light intensity, this is know as Photosynthetically Active Radiation also known as PAR. This will measure light intensity. Kelvin ratings will not make the bulb brighter for a plant, it may look brighter, due again to asctetic reasons. Kelvin although is a legitimately way of measuring colour it was picked up in the 80-90's as a way of marketing 'plant' bulbs, which would cost you $30, and a household/factory bulb would cost you $5.
Plant's cannot use green light as they reflect it, it is best to give it blue and red.
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. Again leaving it down to PAR. Plants uses any light energy in the visible spectrum. Therefore if you can see the light then plants can use it.
some
recent interesting reading...from aquatic botanists and scientists.
http
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/www.barrreport.com/archive/index.php/t-4768.html
My plants did not grow for almost a month until I got new lights. A week later I started using Flourish and I saw even more growth and less algae.
Again, i'm sorry but this has nothing to do with Kelvins. Most aquatic plants are grown out of water and it takes 2-4 weeks for the to adapt to there true aquatic forms, IMO your plants have started growing as they have now adapted and you are giving them some food. Plants are further down the evolution chain than algae and thats why you're seeing less algae.