LED Color Distribution for Planted Tanks

[dmcnamara]

Hey everyone,

Quick question on LED color distribution for planted tank lighting.

I've seen each of the following statements made online, many of which contradict one another:

• Red lights should take up at least 50% of your LED spectrum, while blue lights should not exceed 15% (with the rest, of course, being white).
• You don't want to overdo it with red lights, since having them on for a prolonged period of time will result in excessive algae growth.
• Red lights are useful to the plants that they reach in shallow tanks; however, as blue light permeates further, blue lights should be optimized when lighting a deeper tank.
• Shoot for 75% of your spectrum being composed by blue lights, 20% by white lights, and just 5% by red lights.
• It doesn't really matter, as long as you don't overdo it with the blue lights.

Despite the internet being information-rich for most niches of the aquarium hobby's world, there seems to be limited discussion on this and even less consensus.

Does anyone have input on the matter?


Thank you!

[dcutl002]

The best person that I know of to answer this type of question is jeffkrol on plantedtank.net. Jeff is THE led lighting guru.

[Aiken Drum]

My understanding, to throw further confusion into the mix.

Those red and blue LEDs are such narrow wavelengths of light they do practically nothing for plant growth and its purely down to the output of the white LEDs. The RGB LEDs are there purely so you can adjust how the light appear to your eyes, and the bulk of the actual light output is from the white LEDs.

Remember that white light is a mixture of wavelengths of light across the whole colour spectrum. Red wavelengths promotes long growth and blue wavelengths promote vegetative bushy growth, so you need both, so look for a light fitting where the white light has wavelength peaks at the red and blue ends of the spectrum. Green light isnt all that important to plant growth.

This is the colour spectrum of fluvals plant light output.



If you are planning on keeping those low demand plants then pretty much any aquarium light fitting will be good. Light fittings intended for higher demand plants tend to just have higher light intensity and be targeted more to those red and blue frequencies.

Sorry if ive added some more confusion into the mix. And its not like im an expert here, just passing on my understanding and will follow along as im interested in what others say too.