Ok so the other day when Mike was over here running PAR testing we noted that the PAR was a little less than perfect. Now the question I have is the majority of SPS I have is very very healthy with nice thick tissue (Excluding my resuces). My Softies and LPS are growing and at a pretty consistent rate. Now if the Par isn't at the rate it should be then wouldn't the corals suffer? I know that PUR cannot scientifically be measured, but is it possible that if the light from the LEDs are producing light in a more useable spectrum to the zooanthelle(sp?) then could the coral actually require less PAR then say a MH bulb due to less wasted light?
I have a question regarding LEDs, PAR, and Growth....
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Mostly yes and a little no, lol So in doing research into various LED's and inspecting their spectral irradience charts and also in taking PAR reading I have come to a similar conclusion...so far. When you look at the par readings and spectrals from a MH you can say that the photons being produced are spread over a spectral range of 400 through 700 and change. Now in that range the zoox (their pigments) mostly (mostly like directly) use spectral waves in the violet to blue range, so that would be in the low 400's to 475-80 so lets look at just that then, in terms of growth). Now in the LED world you dont get spectral divercity as you do in the MH world, as in the band tends to be much more narrow. SO in the case of all of the 12-14k led bulbs I have looked at the band is right in the wheel house for the zoox. So with that being said then you could say that more of the photons being produced by the LED bulb go to something the coral's zoox would use.
SO in doing some simple math I would say that a 100 watt HM would put out 70 to 75% of the par that coral zoox use directly when compared to LED's, so their s your yes. The little no part is that corals have evolved by using pigments with in thier tissue to take unusable spectral waves in and flourese them back into a more usuable wave for the zoox. These are the color we see our corals, such as pinks, blues, oranges and so on. Another thing to take into concideration Seth is that corals are very adaptable. So when faced with less light they will adapt by simple allowing for more zoox population, and/or the pigment in its tissue that is now getting bombarded by a certain wave will become more dominate and thus flouresce more and make up small differences. So you have some wiggle room the coral can deal with and still be very healthy.
Mojo
Mojo,
Buried in the reefcentral DIY led thread is some info related to most PAR measurements being 20-30% low based on how the device that measures the PAR handles the 400-480 spectrum. If I remember correctly they took one of the common PAR measurement devices and compared it with a lab grade device and found the difference. Am I smoking something or are most of the LED par measurements low because of that?
-Jim
Buried in the reefcentral DIY led thread is some info related to most PAR measurements being 20-30% low based on how the device that measures the PAR handles the 400-480 spectrum. If I remember correctly they took one of the common PAR measurement devices and compared it with a lab grade device and found the difference. Am I smoking something or are most of the LED par measurements low because of that?
-Jim
Looks like it is buried in the 80 page thread:
Aqua Illuminations LED PAR Readings - Too Low? - Reef Central Online Community
Aqua Illuminations LED PAR Readings - Too Low? - Reef Central Online Community
Ahh here's what I was looking for:
AquaIllumination PAR Measurements - Page 83 - Reef Central Online Community
AquaIllumination PAR Measurements - Page 83 - Reef Central Online Community
I dont know if you could say 20 to 30% Jim, lets take a peek at it
So you could say that the apogee is accurate up to the 440-450 wave, then it drifts off and become accurate again at the 580 zone. Zoox pigments like the zone 400 say to 475 (approx) so we are talking a percentage difference in only about 25 wave lengths. Regardless I think it would be safe to make the following claims.
>that LEDs of a decent wattage will grow and color corals
>Led's put out light in a narrow band so one must becareful of over loading the corals with photons and thus causeing them to bail their zoox, so having a dimming control would be a wise move and then slowly acclimating them (as you would with new MH) is a smart thing to do.
> Because of the narrow band it would be wise to suppliment them with red LEDs to hold the color of corals that look Red/Pink to our eyes.
> That they seem to loose most all of their photon output when you move away from directly under the lights. So a narrow band based on the optics, Now I have only seen the most popular optics, but I would concider them not very good. I am going to do some testing on LEDs without using any optics and then usinf reflectors in their place to control light bleed off. We will see how this pushes light from side to side.
mojo
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Here's the chart for the LEDs I was looking at. I think that's why people were saying it's about a 20% drop off for measuring the royal blue leds. Which is different than reading 20-30% low (which is what keeps getting repeated).
In the grand scheme of things I'm not sure how much the 20% on the blue matters. If blues are 20% low and you're only measuring blues you'll see it. We don't just use blues though, you'll have a mix of white/blue so even at a 60/40 ratio for a very blue look it's probably reading maybe 12% lower than it should.
Yea it gets all kind of fuzzy at some point. I think if we get to anal about it we are going to basically not see the forest through the trees. Thats why I put out some general statements, their is alot of products out their right now that are not viable, and in the same breathe their are some that are. I think the main thing we need to know though is that its not cut and dry to measure them as we would a MH light.
Mojo
Mojo
