Can someone answer a LED per level question?

[reefslugs]

I can not find a straight up answer on LED light par levels. My question is, do the blue LED bulbs have less par levels then the white bulbs?

[Djbeasley05]

420nm wavelength is proven to penetrate water the easiest. This is somewhere between violet and blue color wise.


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[smoothdog]

I can not find a straight up answer on LED light par levels. My question is, do the blue LED bulbs have less par levels then the white bulbs?

Unfortunately, that's because it isn't a simple answer. We measure par with available industry standard meters which are designed for terrestrial use (plants) where the blue spectrum is only a portion of the wavelength measured. Since water filters out most of the other spectrums rather quickly as depth increases, the over all par decreases when measured under water but the blues penetrate very well. In order to compensate for this, photosynthetic organisms that live under water (AKA coral) tend to be more sensitive to and reliant on the blue spectrum.

So when you measure with a PAR meter, the blues only may show that there is less par than white, but for the coral, that blue light is more usable than the other spectrums found in the white light. So technically in coral, blue light has more critical par than white light of the same intensity.

The take away here is, don't crank up your blues to compensate for lower par readings than the whites, you are likely to burn up your corals by doing so.