LED questions

I've tried to research this question online but can't really find a direct answer. So, i've got a RapidLED kit for my biocube 29g. It's the Dimmable version. I've been messing around with the blue vs white balance and I actually probably prefer more blue most of the time which makes it look like pure actinics. what I'm wondering though is if there's a difference in coral growth if you use more white opposed to blue. Does color in LEDs affect corals at all? Do corals even notice if (hypothetically) you're changing the color temperature all the time throughout the day? 

There's actually quite a bit of info available on the internet re LED colors and corals and how the light colors may affect a coral's ability to maintain the zooxanthellae algae that lives in their tissues.  But from what I've seen, much of the research also involves the depth of your tank, how far the different colors penetrate, etc.  For a Biocube 29 I think I'd be more concerned about too much light, than not enough, if you are using LEDs.

I don't know much about leds as we just upgraded our 120 to them. I'm glad you posted this so I can fallow as well. one thing I have noticed though is the difference in our coral. The lps is loving the change but our softies do not. We run the whites a little brighter then the blues mainly because the lights we had before ran more whites then Blues and I don't want to make big of changes risking our corals health. I think, not that I really know, that corals notice and are effected by color temp changes. I can only theorizes on this though but my thinking is this, in the ocean with natural sun light, color temps are changing all day and all night, corals are exposed to all forms of natural sun light at any given time for example direct, cloud coverage, season and so on. Corals thrive in what's naturally given to them. Knowing that I have set the lights to fallow the earth's lunar cycle so the color temps are changing in our tank all day as well as throughout the yr(longer days and shorter nights in summer and vice versa in winter) I have observed that depending on the light cycle time will depend on what my corals look like. Mid day in summer my lps is looking killer but different species of my mushrooms not so much. Sunset or sunrise mid summer different species of mushrooms are looking killer were as my lps not so much. So to answer your question yes I think corals are very much so effected by different color temps just based on what they are exposed to in the ocean then taking that knowledge to my tank. No education or research in my answer so I may be wrong.

Coral response to different wavelengths is partly due to the depth of ocean they typically live, but we also know that they can adapt. I have seen pics of clams at 60 feet where it's just blue (see images below).

MH research may overlook the fact that it's the greater intensity of light emitted by MH bulbs of the 10,000 - 14,000 Kelvin variety that makes coral grow fast. On the other hand, for 3 years I used an old 400 Watt 20,000K MH situated about 1.5 feet above the coral in my coral frag tank. The bulb was over 2 years old when I installed it, making it over 5 years old when I sold the system. Everything grew very fast with plenty of color the entire time.



Even though a light appears white to our eyes, the spectrum that it actually emits is just a few narrow wavelength bands. Notice how Nikki/ReefdUp, who has done a ton of research,  is using 6 different LED colors in her DIY LED build here: http://utahreefs.com/forum/forum_posts.asp?TID=66671  Color/spectral output does matter.

What happens as light passes through water? The images below may be a helpful demonstration. I scanned these from a Jacques Cousteau book I checked out from the library many years ago.










Edited by Mark Peterson - September 23 2013 at 4:25pm