I was wondering what light spectrum will enhance red plant growth while maintaining the beautiful colours ? Given the light intensity is high and all required nutrients are in the tank, I have found two options. Although I graduated biology, my area of research was not plant science. Maybe there is somebody here who can enlighten me. My thinking is this. Red plants will mainly absorb light in the blue spectrum so the peak there is beneficial. However, the red peak will serve to enhance the look of the carotenoids , making them look red not brown. The red peak will also benefit green plants as chlorophyl a and b have their "second" peak absorption in the vicinity. Nevertheless the absorption of red light is higher in water, so maybe option 2 is only useful in shallow tanks. Questions that arise are: Why ADA and other manufacturers promote Option 1 as good for plants ? and Is there a possibility that the red peak prevents plants from turning red (there is useful radiation there afterall) ? Option 1 - 7000K - ultra white ( maybe something like this is used by ADA aquasky cannot find a sure graphic of their spectral distribution in english) - peak around 425nm Option 2 -15000K - blue red white -peak at 465nm and 650nm Thank you for your opinion. Searched the forum and could not find a relevant discussion on this topic. PS The Spectral distribution graphs come from this great company called Daytime here in Germany. They have the copyright. I cannot yet post links otherwise I would have included one. If you have any experience if this company please do tell.