More material supporting sub 500nm wavelengths! Well, for better color, that is.

[Joe Lydon]

You don't have to purchase the full article. The short version is pretty rounded. You have to click "Look inside". Seems that corals provided with wavelengths below 500nm, simply adjust their pigment to better utilize the incoming light for photosynthesis. Intensity, will obviously exacerbate the effect! So, in theory, if you eliminate wavelengths above 500nm, you will force the coral to morph into pigments that fluoresce and help photosynthesis efficiency? (or at least, this is what my less than highschool education tells me!)

http://link.springer.com/article/10.1007/BF00317092

 

[wld1783]

I have found the Cree 450nm Royal Blue the best bang for the buck when it comes to Photosynthesis and colour pop. Any thing above 460nm I noticed a significant drop in fluoresce. Here are a couple graphs that are also useful.

Bill

 

[Joe Lydon]

I wonder if that's why people who use only 10k lights get good growth, along with people who use a very heavy blue spectrum, versus those who try to incorporate both. Are those corals being subjected to both ends, becoming confused on which pigment to display? Seems like they can adapt to one or the other. Also explains why colors are better on corals that are grown under a shorter wavelength. Those pigment adjustments just happen to be nicer looking, to us.

 

[jm23]

In my experience each individual coral likes a certain spectrum. I think the Royal Blue LED is the cornerstone to a good LED build, but having those whites (Cool, Warm, and Neutral) is just as essential as your blues (Violet, Royal, and Blue). My DT does not get as nice of colors as my FT and I believe the reason for that is my display does not have any Warm or Neutral White (that will change as soon as the mailman gets here today). Those graphs are a good reference for why both ends of the spectrum are important.

 

[wld1783]

I've grown frags using only Royal Blue. Growth rates were the same or better as compared to the MH.

Here is an interesting chart that relates to depth and spectrum. Corals of the same species are often found at a wide range of depths.

Bill

 

[wld1783]

I forgot to mention looks.

Corals reach photoinhibition between 300-500 PAR.

After that they either adjust their zooanthellae algae and or develop pigments to reflect the excessive light.

I was asked to help Battle Corals replace their 400 watt 6.5K iwasaki MH with LED.

The surface PAR of their 8" deep propagation tanks was over 1100 PAR.

The corals looked lousy under the 6.5K but the same coral moved under a 20K Radium looked awesome. The theory is the coral developed extra pigments to reflect the excessive light.

We wound up producing a DIY fixture that consumed only 200 watts with the same PAR. The look was much better than the 6.5K MH. Some of the corals developed better colour others browned out.

The LED Mix was the Cree XT-E Cool White and Warm White as they offer a full spectrum, 450nm Royal Blue and Blue. Now we are experimenting by dialing back individual LED banks to find the optimal long term looks and growth.

Finding the optimal look & growth is a bit of and art/challange. Ask any Radion owner about adjusting their fixture.

Bill