Royal Blue dilemma, Cree vs Rebel

[rO.oster]

As you may well know, there is a difference between the peak and spread wavelengths between the two manufacturers.

 

The Rebel ES's are roughly 445nm with a 20nm spread, while the Cree XTEs are 455nm with a 15nm spread.

 

The question is for those of us running 700mA drivers, dimmed down.

 

I've read you can balance out the purple effect caused by the Rebel Es with 475nm Blues, though it seems adding the blues is beneficial to coloration no matter which brand you choose.

 

Its surprising the difference 10nm will make in coloration. Yes, "its close" but its also not.

 

Certain retailers claim "The 450nm-455nm XT-E Royal Blue which is the perfect wavelength for color/growth of LEDs. Wider, less accurate wavelength LEDs that range over 20-25nm are not grouped with our LEDs. We also do not carry anything under 450nm because of the sharp decline of coral photosynthesis under 450nm."

 

While others claim "When compared to the Cree XT-E, these have a deeper blue with more actinic light, and appear to be approximately 10% brighter. - Wavelength -440-450nm <- This is the lowest offered by Philips! Lower is better. The lower the wavelenth or royal blue, the more iridescence or "color pop" your corals will have."

 

Of course, Im basing all my observations from specs and paper data. I am looking for the experiences of those who have faced the same decision. What direction did you take, why, what did you supplement to provide balance, etc....

 

This is for my full spectrum build which is nearing maturation, based largely upon Rebel ESs. Exact specs found in the OP of my tank thread found in my siggy.

 

P.S: I am ALL about the CRI and appearance. My application does not need powerful LEDs and high amperages/output. My focus is purley on asthetics.

[AlanM]

Im interested in this as well. About to pull the trigger on my emitters. I feel like this must have been answered in the past, but i cant really find a pro/con and of course each supplier says that theirs is better.

 

Is it just a choice of american leds made in china or dutch leds made in china? Heh

[fishnlou]

I have been wondering this myself for quite sometime. I dont understand the claim that anything under 450nm has a sharp decline in photosynthesis. I would really like to see some facts proving that statement. I like the deeper purple look so i went with rebels, plus ill be using cool blues incase i need to cancel some of the purple out. Looking forward to hearing some of the more knowlegdable/experienced memebers opinions on this one.

[1reefluvr2]

The purple makes a better color pop?

[MeepNand]

Certain retailers claim "The 450nm-455nm XT-E Royal Blue which is the perfect wavelength for color/growth of LEDs. Wider, less accurate wavelength LEDs that range over 20-25nm are not grouped with our LEDs. We also do not carry anything under 450nm because of the sharp decline of coral photosynthesis under 450nm."

I think that's wrong. There was a link in Jedi's sig about zooxanthellae absorption spectrums, and 430nm was the best. So rebel ES are definitely better. No to mention cheaper.

And purple is known to cause coloration. I never thought there was a particular purple tint to the ES royal blues (I have a few over my terrarium) but I'll test it out over my aquarium in a few.

[blasterman]

I've run tanks with various incarnations of royals all the way down to 440nm and noticed no difference in coral growth. Talked to several guys running ReefBrites and such in this range and they also report no difference. There might be more energy in shorter wavelengths for chlorophyll reactions, but it's a test tube arguement only. A billion other things going on in our tanks that are more important than peak -vs- dominant debates. We're already saturating our tanks with more LED light than we need.

 

Philips Rebels have a dominant wavelength of around ~448nm with some variance of bin-bingo. Cree XT-Es royals around 452. This was as about a year ago when I last verified it with my spectrometer.

 

If you had two tanks side by side lit with nothing but royals of each you would notice the Rebel tank was a bit more purple. Our eyes have a greater photopic sensitivity to the longer wavelength, but it wouldn't be perceptible. The 440s I used to run though did produce a bit darker tank per the same energy level.

 

In any case, I prefer the color of the Crees over the Rebels, but it's a very minor. I run neutral heavy tanks, and the slightly more purple tint of Rebel royals isn't as desireable as Crees. Also, a 470-475nm emittes produces FAR stronger actinic reactions than a 448 or 452. I proved this in the Aethestics thread. However, 470-475nm emitters need to balanced with extreme care.

 

 

 

I am ALL about the CRI and appearance.

 

Put your mental efforts into a good layout to reduce disco flicker and get even coverage, and ignore BS marketing in regards to types of Royals and PAR because it's just that, BS. Halides have an even narrower spectral range in their peak wavelength, and nobody has trouble growing corals with those. Everything being equal I prefer Royal XT-Es just a smidge over Royal Rebel ESs for color, but I'd have no issue going Rebel ES if the price were good. However, I do prefer Cree standard blues over Rebels because every standard blue Rebel I've bought is closer to cyan and far greener than I want.

[rO.oster]

If you had two tanks side by side lit with nothing but royals of each you would notice the Rebel tank was a bit more purple. Our eyes have a greater photopic sensitivity to the longer wavelength, but it wouldn't be perceptible. The 440s I used to run though did produce a bit darker tank per the same energy level.

 

In any case, I prefer the color of the Crees over the Rebels, but it's a very minor. I run neutral heavy tanks, and the slightly more purple tint of Rebel royals isn't as desireable as Crees. Also, a 470-475nm emittes produces FAR stronger actinic reactions than a 448 or 452. I proved this in the Aethestics thread. However, 470-475nm emitters need to balanced with extreme care.

 

Put your mental efforts into a good layout to reduce disco flicker and get even coverage, and ignore BS marketing in regards to types of Royals and PAR because it's just that, BS. Halides have an even narrower spectral range in their peak wavelength, and nobody has trouble growing corals with those. Everything being equal I prefer Royal XT-Es just a smidge over Royal Rebel ESs for color, but I'd have no issue going Rebel ES if the price were good. However, I do prefer Cree standard blues over Rebels because every standard blue Rebel I've bought is closer to cyan and far greener than I want.

 

 

Good information here.

 

I think the progression of understanding has certainly evolved for LED arrays that use quality manufacturers like Cree and Phillips. We have so much PAR at our fingertips, and coral are very adaptive at being able to adjust to available spectra from the most basic LED arrays (such as CW/RB). You could easily skip all exotic colors, and still grow coral like crazy.

 

The point in discussion is the impact of Cree XT-E vs Rebel ES for visual aesthetics Since the Royal Blue channel carries a majority share of presence in our arrays, the small differences deserves consideration when deciding on the direction.

 

 

In any case, I prefer the color of the Crees over the Rebels, but it's a very minor. I run neutral heavy tanks, and the slightly more purple tint of Rebel royals isn't as desireable as Crees. Also, a 470-475nm emittes produces FAR stronger actinic reactions than a 448 or 452. I proved this in the Aethestics thread. However, 470-475nm emitters need to balanced with extreme care.

 

Since I think the majority of us are running 4,500K dominant neutral arrays, can you explain in more detail how the Rebel royals turn you off? I've also read to use caution with 475 "Cool/True" Blues, and how they can make a tank look Smurfy. Uug, Smurfy, Windexy, Purpley... I realize these are all personal observations translated to descriptions we can all grasp and understand, but it makes it hard to try and plan a direction.

 

Obviously the best way would be to buy and test each brand/array to understand what your preference would be. But realistically how many of us can do a side by side comparison to feasibly test the delta between two configurations? Even taking a photo log to do comparisons via the computer is not a good way, as the variations of white balance and photo conditions do not permit a controlled test.

 

What about the claim that the Rebel royal blues are "brighter" (not PAR intense, but perhaps visually brighter)? I've noted before that the recommended ratio of Rebel Royal:Neutral White is 3:2, while Cree XTE:Neutral is 2:1. Why is this?

[eklikewhoa]

I run a mix of both

[ajmckay]

If I recall there are some comments on the cree vs. rebel debate on the full spectrum thread. It's been a while since I've read it though so i can't be 100% sure.

[rO.oster]

Can anyone else share their experiences?

[ajmckay]

Honestly I don't think it matters a whole lot, they're both reputable brands with solid performance over reef tanks.

 

I would take blastermans advice (very knowledgeable guy btw) and focus on creating a layout that will give you even coverage with no disco vs. worrying about which brand of LEDs to get.

 

When I built my LED array I faced a similar dilemma just a few weeks ago and ultimately made the decision based on which LEDs were most economical (including shipping, drivers, etc...). Part of the fun of DIY I suppose is gathering all the materials and testing it out, being prepared to switch it up if you're not happy with the results.

[Chris155hp]

Interested in this

[basser1]

Lots of good info here, maybe it can help....

 

http://www.nano-reef.com/topic/352618-led-colors-and-what-they-are-used-for/

[Paleoreef103]

Honestly, it doesn't matter that much. If I were you, I'd pick my royals on the basis of several factors that don't actually deal with the royal blues. 1) where am I ordering my LEDs from? Most retailers specialize in either Cree or Rebel. 2) Which white LEDs am I using? I generally prefer rebels here for better color rendering. 3) Where am I getting my violets and other color LEDs? For Violets I prefer LEDgroupbuy's violet range (who specialize in Crees. I also prefer their 465nm Blues). For color LEDs (Limes and Cyans in particular) I patronize Steve's LEDs who specialize in the Phillips Rebel line. 4) Where am I buying the rest of my equipment?

So. I'm afraid I didn't help you too much. If I was building from scratch, at this point I'd resign myself to the fact that I was buying from places that would let me get both and probably get a 50/50 mix of each. Yes, the rebels are GENERALLY closer to the photosynthetic peak, but the difference isn't that big where I clearly favor the rebels. IF I was trying to use 3-ups as the primary basis of my set up, I'd probably go rebels, but that's mostly because I really enjoy their whites.

[blasterman]

All things considered Cree Royals in their typical 450-452nm range tend to a look a bit 'crisper' than the rather 'violet' hue of Luxeon Royals (447-448). It's subtle, and highly subjective, but Evil and I agree we prefer the Cree wavelength a bit more.

 

The big difference is Luxeon M Royals....and the lack of a Cree substitute. The power density of Luxeon M Royals can't be dismissed, and combined with the smooth rolloff of the Ledil Reflector I'm willing to dismiss Cree royals. Why screw with with 3watt royals when you have a 12watt one available.