[Kolognekoral]

Originally Posted by blasterman789

The aethestics issue aside, I have no idea why we're still debating about LEDs producing good, legitimate PAR. I've seen enough wildy growing SPS tanks under LEDs with a fraction the power of the halides being replaced to more than be convinced. Color might suck, but that's a different issue, and the Cree Cool-White cult won't change their mind anyways because they can't tell the difference between LED steet lights and reef lights as long PAR meters are pinging numbers at them.

I think you might be being a bit too hard on the CW followers. (and i had thought the 'enough PAR' issue was well behind us, but maybe I am naive) I don't see this as being any different to the 10K people vs the 20K people. It really is aesthetics. I like a warmer note to the tank and refrain from the black light look, but that is me. Friends ask why my corals look different than those in the shops, but it is simply the lighting. Fashion, if you will. Neither here nor there, really.

Originally Posted by blasterman789

Corals want deep blue light. Its just an evolutionary adjustment to growing under water. There is some debate about shallow water corals like Acropora that frequently grow into the air at low tide possibly being able to utilize warmer wavelengths, but evidence is sketchy. Some other evidence that an abundance of red light tells the coral 'Hey, moron, you're growing above water in a tidal zone, stop it."

LEDs are extremely efficient at producing far blue light in the 455nm range, and it's the one thing they do well. Last spring I did a test where I hit Acropora frags with single 3watt LEDs of various colors using 10 degree optics just to see what would happen. A cool white Cree R2, and Red and Green K2s had no effect on the Acros (miami orchid). However, a regular blue Cree caused the Acro to bleach badly in less than 36 hours. This was pretty much all I need to confirm that blue is action spectrum.

I agree with you on this, the corals don't seem to require the far red spectrum at all, they are simply adapted to it in certain species/forms and may be able to utilize it, should it be available.That's like people eating certain foods as they are in season. Most of the info I've found concerning chlorophyll spectra is based on land plants and then translated to zooxanthellae. This simply gives a skewed picture as to the corals actual needs. And, as I mentioned previously, corals are predatory as well, they are capable of feeding themselves to a large degree. Their ability to regulate their metabolism is hardly researched and the various mechanisms are not understood. We have a great deal to learn, here, but we can still manage a good spectrum without understanding all of the mechanisms.

Originally Posted by blasterman789

Biologists I've talked to seem to be mixed on where the maximum action spectrum is for zooxanthellae algae. Some say it rides with the clorophyll A line at around 440nm, and other say pretty much any strong blue spectrum is sufficient. Looking at Sanjay Joshi's spectral plots of Reef halides all show a common denominator, and that's massive amount of light at around 450nm. So, if I were a betting man, I'd say that spectral energy at 440-460nm is 'happy time' for corals. This confirms all the happy SPS tanks I've seen with LED

The need for blue deeper than LED royal blue (below 455nm or so) is sketchy. For aethestics, yes, by all means light deeper than what royal blue LEDs can generate looks really good because there are some 440nm reef lights out there, and they look fantastic. Is it required for better zooxanthellae growth? I just don't know, but it woulndn't seem so.

Absolutely, the 440-460nm range seems to be most suitable, but the question for me still remains, it the 440-450nm range crucial for the corals or not. Current Cree LEDs do not reach this range in real amounts (the NW does dip that low). If the zooxanthellae are not crucial to the corals well being, then this range may be unimportant for basic care of corals. Chlorophyll b is well served by the Cree LEDs.

Originally Posted by blasterman789

There ARE 440nm lights out there; I think Reef Brite or Sun Brite make them. PJR is running them on his SPS tank over at Michigan Reefers and his growth is nutz.

I screamed and yelled and finally got somebody to make some 10watt 445nm LEDs, and I'll be happy with my victory. However, as I've said in other thread, the DIY community is obsessed with Cree, and if Cree doesn't make 440nm LEDs then the reason is 440nm must suck.

The hole in the spectrum of white LEDs at around 485 isn't a concern of mine since this color would be a combination of Windex and green Lysol.

OK, I have not found any hi-power LEDs between 400nm and 450nm. Can you give me a link? I would suspect that this range, as well as the range above 630nm is uninteresting for LED manufacturers, as the lower range is only needed for irradiating with UV, that is below the 400nm range and the higher range is simply largely heat and not conducive to LED longevity.

I wouldn't write off the 505nm to 550nm range just yet. This could be interesting, if not important. I just don't know one way or the opther. Do you have any specific references? or is this just personal aesthetic?

Originally Posted by blasterman789

Where? I'm looking at Sanjay's graphs and don't see 680nm anywhere. Also, far red is very difficult for fluorescent phosphors or halides to produce, which is why high pressure sodiums are preferred for agriculture use. Also, at 30feet under the ocean you could probably count the number of 680nm photons penetrating that deep on one hand. Does it matter to an Acropora growing above the water on a reef? Maybe......

Last, I really, really am skeptical of readings from PAR meters because unless it's calibrated specifically for reef use it's feeding numbers likely not optimized for corals. Red light light is critical for dope and tomato growing, but doesn't mean much to corals. However, general use PAR meters are going to key off of red light because that's their intended market.

This explains why I've seen some reefers get higher PAR numbers from white light LEDs than dedicated blues. The PAR meter is reading spectra that will grow a tomato plant, but not ideal for acropora. This is why I'm far more concerned about actual spectral plots than PAR readings.

In any respect, I give this thread a '10' on a scale of 1-10 because were actually talking about data and not brands.

I suspect many of our corals come from about 10m depth and the red spectrum is not really present under 5m. I have a few wild colonies from much deeper and they certainly do not require red. I would suspect that only a handfull of collections have been adapted to tidal conditions. I think we generally agree on this, but others please chime in with opinions. Most HQI bulbs have little red in thier spectrum, but the lower K rating do have some. As to T5s, I don't use them and cannot really comment, plus, those spectral data I've seen do not seem to be representative, as spectrum in tubes changes rapidly with age and phosphor mix. Halides as well for that matter. I see LEDs as having a big advantage in the realm of spectral stability, but maybe this is not true. Data, can we trust it? Is it too early in this technology to be certain?

Thanks for the 10 rating! I suspect some interesting ideas will pop up on this thread, as well as the sister aesthetics thread.