I don't often see somebody flashing their "credentials" but now you've done it.
First, being a communication technician gives you little authority of opinion in this field than many others would have. I know because I employ communication technicians. (www.orbitaldata.net
) Mr_X has an enormous amount of experience as I have had and many others on this excellent forum. So let's all lighten up and let's be courteous.
All lights make photons. Period. Some make more photons for the energy usage and some make broader spectrums for the energy they consume. Some produce large amounts of waste heat. They all grow coral if strong enough. My basement full of 25 years of burnt out bulbs, both MH
and T5 prove that. My chiller also proves MH
are expensive to operate because of waste heat generation.
There are just a few emitter manufacturers, Kessel doesn't make their own, few of them do as I am aware. The best emitters are Cree IMO
. Kessel uses DiCon dense matrix emitters. These are efficient and tiny but can be prone to failure in some applications I've used them in. But they are elegant and work well. Not sure of any fixtures using "garbage bin" emitters. Not a productive comment as no one wants to be told their light is garbage.
This is a old beaten up topic that I thought was put to bed years ago. The proof in the pudding is the thousands of photographs of highly successful SPS
reefs using all varieties of high output LEDs. Especially cheap Chinese panels. The Chinese product have lousy drivers but grow just fine. Again, JMO as I imported about 100 of them.
Just for reference:
PAR, or Photosynthetically Active Radiation designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds "more or less" with the range of light visible to the human eye.
PUR, or Photosynthetically Usable Radiation is that fraction of PAR that is absorbed by zooxanthellae photopigments thereby stimulating photosynthesis.Photosynthetic zooxanthellae in corals and some other marine invertebrates utilize light in the 400 to 700nm range in different ways.
PAR will always be a greater value than PUR.
The lumen can be thought of casually as a measure of the total "amount" of visible light in some defined beam or angle, or emitted from some source. The number of candelas or lumens from a source also depends on its spectrum, via the nominal response of the human eye as represented in the luminosity function. (Wikipedia)
So lumens is appropriate for measuring energy delivered to your eye or thru a camera lens where the breath of the bandwidth absorption is much greater than with plants or corals. But it can still be used as a relative measurement of lighter vs darker areas.
One other note, any amateur PAR meter used to measure LED
output needs to be corrected for the narrow spectrum spikes. These correction factors are available on the Quantum web site.
Whew. That was the longest post I've done in a while.
Happy reefing and peace brother.
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