[ScubaSteve]

Originally Posted by mrhasan

You cannot make the same color pop with the same color supplement. The theory goes like this:

To pop something "black", you will need "white" background and vice-verse.

Let's look at the RGB spectrum:

Basic rule, you have to have the contrasting color to make coral color pop. If you look at the RGB intersections, the best pop for red will be when you put in cyan. SO you will have to mix the RGB strip accordingly to create cyan blend.

Errr... That's not necessarily true. When you see a red shirt, for example, you are seeing red because the shirt is reflecting primarily red wavelengths while absorbing most of the other wavelengths. So, if you were to shine a light on that shirt that was missing red in the spectrum, the shirt would basically look black/brown. No amount of cyan is gonna make that shirt look red. And this is where a lot of misconception comes into the whole LED schmozzle...

Corals have two different types of proteins that give rise to colors: chromophores and fluorescent proteins. Chromophores behave like the red shirt in the example above: they absorb certain wavelengths while reflecting others. You can accentuate these colours by hitting them with the colour that they are. Purple is a prime example of a colour coming from a chromophore. Often you see chromophores in growth tips of SPS there the tip is a different colour than the rest of the coral. Chromophores are Antioxidants and act like sunscreen for the relatively new flesh of the coral, which matures over time to contain more...

Fluorescent proteins. There are three main types of fluorescent protein: green (GFP), cyan (CFP) and red (rFP). These proteins behave different than the chromophores because rather than reflecting a particular wavelength, the emit a particular wavelength after being excited by a more energetic wavelength. So, for a red coral (whose colour comes from rFP and not from a chromophore), red light does dick all to enhance the red coloration. But, as you notice, when you hit that coral with a higher wavelength, like in the cyan region, the coral goes all psychedelic on you because the rFP is fluorescing (which is what gives corals that "pop"). This is why TV, RB and cyan bring back a lot of the "pop" that goes "missing" when people swap to LEDs.

Even within the GFP, CFP and rFP clades (ie. similar proteins), there are a number of proteins which all have different absorption and emission peaks. This means, for example, each rFP has a different peak excitation wavelength and different emission wavelength. Metal halides are a continuum of wavelengths, so we get that spread that covers all of the different excitation peaks and we see a balance of coral colors (though you may also notice a lot of people with halides still use T5 or LED lighting to supplement the MH and bring out other colors the MH miss).

LEDs, on the other hand, have more discrete emission peaks which, if you only use one or two types of LEDs, leaves big gaps in the combined spectrum. This in turn leads to certain colors, be it a chromophore or fluorescent protein, not being rendered. Yes, by moving towards a full spectrum you start to fill in those holes, but you still don't have the same spread that a MH does, so some corals look WOW! And some look BLAH!.

Then there is also perceived colour temperature. With just CW or NW, the tank has a yellow hew. By adding RB the tank looks more like the 14K halides we are used to but still has a bit of a sterile feel to it. By adding reds into the mix you start to add a bit of warmth into the colour (and really it doesn't take much red to do this). The addition of red doesn't actually positively effect the colour of many corals (rFP isnt excited by it and there are few orange to red chromophores). It's the mix of colours that effects more how your rocks and sand look to you, which actually plays a big part in how the tank looks to you. For example, if you used all TV and RB, everything would fluoresce like mad but to you the tank looks like blue soup because your rocks and sand look blue. But if we kept the same coloration in the coral but change the sand to white, the tank has a totally different feel to it (and would look awesome).

So, to really have a good full spectrum LED set up (or any lighting set up for that matter) you need to understand where the colour of your corals are originating from and pick your light source to accentuate the different colors of your corals. The colors of our corals originate from different processes, so we have to take this into account with the design. And there are also the colors that we need to see to balance everything out.

This isn't even getting into the whole photosynthesis argument. I'm not going to touch that one but I'll just leave it with: find a colour mix that works for you and get lots of LEDs

Originally Posted by Madreefer

I've supplemented my AI Sols with 2 Ecoxotic RGB modules. When the reds are turned on it does not pop the reds at all. I find the rdes pop more when the blue is turned up more. I'm waiting for the new controllors for the said supplemental lights and will be adding 2 more for more options to play with.

See above.

Originally Posted by daplatapus

I think some of the problem when talking UV is there really is no standard. What's being used in LED's when they say UV isn't really UV, it's true violet or some form thereof. I've read of TV LED's ranging from 395nm to 410, 410-420, 420-whatever. But because these LED's are putting out only those wavelengths you have to have a mix of them all to really call it a FULL spectrum build. That's pricey. It's why you're not seeing it being done in commercially available products. Heck, I still haven't seen DIY builds doing all the spectrum, there's still arguments about which ones are even being used.
But with MH, just turn it on and you at least have some amounts of everything.
Even if a specific coral uses only .5% of a certain spectrum in the wild, that .5% is still going to affect it's coloration and growth to some extent if it's not provided. It may still be able to live and grow, but not as well. Until someone comes up with an LED or fixture that incorporates everything that a coral needs for a certain look an individual wants, you won't get the "pop", florescence etc. you're looking for. And it's going to take someone with the time, money and perseverance to try and try and try again to figure it out. That's how anything progresses.

You don't need to have an LED for every chunk of the spectrum to do a proper full spectrum (in fact look at the spectrum of some halides and you'll see that they can totally drop out at some wavelengths and are super heavy in other areas). And because LEDs do have a distribution in wavelengths (some tighter than others), some of the tails over lap and add up. Also, you don't really need to cover all the spectrum in the UV/violet/blue range since much of these wavelength contribute to fluorescing colors while being mostly invisible to our eyes. So long as you have some wavelengths shorter than the RB, you're pretty covered as the photons less than 450 nm are energetic enough to make most colors fluoresce.

So, you can build a fairly nice, continuous spectrum with a limited number of LEDs. We certainly need more than the RB/white mixes of old but we don't need to go overboard either.