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Best LED mix for freshwater

18100 Views 34 Replies 13 Participants Last post by  Milad LEDGroupBuy.com
I plan to build a LED fixture for a 15G tank and I would like to know what is the best LED mix for a freshwater palnted tank?

I plan to use Cree XP-G for white and add some red XP-E for red. Or should I also add royal blue?

I found this nice graph of PAR sensitivity (the red line):


Should I try to mimic it?
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I'd like to do something similar. I did a string of blue leds on my reef and it really rocks! I'm thnking for my planted tank I might do a combination of XP-G which is around 5-8K and cool white XR-E which is around 6.5K. Not sure about the red. I got mine at Rapidleds.
Last I looked into this, nobody is producing a high power red led in the 660ish range. Or if they are we can't get it yet. (may be wrong) Is this for looks or plant growth cause if its for looks then that wont matter much!
Plants grow when they have enough light, whether the spectrum is close to matching that graph or not. Pick what looks best to you. But, I don't know how you can do that without first building the fixture. If the LEDs are not closely spaced, the red or blue LEDs will give you colored spots on the substrate. If I were to do this again I might mix cool and warm white, but not add any red or blue ones.
Plants grow when they have enough light, whether the spectrum is close to matching that graph or not. Pick what looks best to you. But, I don't know how you can do that without first building the fixture. If the LEDs are not closely spaced, the red or blue LEDs will give you colored spots on the substrate. If I were to do this again I might mix cool and warm white, but not add any red or blue ones.
Similar to what I said, skip the reds and just alternate the whites so you don't see the different colors at different parts of the tank. I'd also use 60 or 80degree optics which spreads the light rather than having narrowowly fucused bright spots.
Last I looked into this, nobody is producing a high power red led in the 660ish range.
Well, I found a 660nm 1W LED on fleabay, but it is of Chinese origin. And a 440nm 1W LED too.

On second thought, mixing those crazy LED colors would make the tank look ugly. Maybe an alteration of warm and cool CREE whites would be enough. Also I have noticed a new type of XP-G LEDs - the 90-CRI, did anyone had a chance to use them?
I am getting ready to plunge in to LEDs (I love the driver you linked to recently, Hoppy), and had a similar question. What do those who have done DIY LEDs think about the pleasantness of the color? Does it seem fairly flat and monochromatic? What would you do to make it look better?
You get used to whatever light you use, so even though it may appear to wash out the colors on the first look, it soon looks normal. I used all cool white LEDs, and it does wash out the colors a bit. I suspect that a mix of warm and cool white would look better, but I haven't tried it. As LEDs get better, there will very likely be some better choices to make.
I am in a similar bind: want to make a light for wife's 9 gallon ADA tank as a Christmas gift. The tank is roughly 18"x9"x9". How many LEDs would I need? Would it be possible to create an appealing light spectrum? How many lumens should I target? Would using two of a Cree PAR-38 assemblies create too much of a spot-light effect? Where is a good place to buy everything? Is there a one-place stop shop where LEDs, heatsinks, and whatever else is needed can be ordered from?
Is there a one-place stop shop where LEDs, heatsinks, and whatever else is needed can be ordered from?
I think that you will need 7-10 Cree XP-G "outdoor white" at 350mA. Unfortunately there is no one-place shop (maybe RapidLED.com), because you need soldering stuff (soldering iron, solder, etc.), LED stuff and metal.
I think that you will need 7-10 Cree XP-G "outdoor white" at 350mA. Unfortunately there is no one-place shop (maybe RapidLED.com), because you need soldering stuff (soldering iron, solder, etc.), LED stuff and metal.
Thank you for the reply. Could you elaborate why you specifically say "outdoor white". From my research I saw people using cool white or a mix of cool whites with warm whites. Are outdoor whites give a pleasant spectrum without having to mix?

Also, you say that I should get 7-10 of those. Ten would give something 1300 lumens. I was thinking I would need on the order of 3000. Am I mistaken?

As for the soldering stuff, I already have the iron and the solder. I am fairly electronically literate (build hifi vacuum tube amps as a hobby). I guess, LEDs, heatsink, and maybe a power supply is all I am looking for to buy at first.

Jenya
Outdoor whites give a spectrum similar to cool+warm. In my 15G tank I have 12 neutral white @ 350mA + 2 Royal Blue and it is a little bit too much.

You can buy a 700mA LED driver with dimming and fine tune the LEDs.
Thanks for clarifications. I am having the hardest time trying to find a place that sells XP-G outdoor. Digikey sells them in minimum quantities of 1000 only.

Are the heatsinks from RapidLED a good way to go for this?
Check ebay too, lots of cheap surplus heatsinks there.
So, I have carefully studied the docs and the conclusion is that Outdoor whites are not suitable for a planted tank - they have a low kelvin rating and color rendering index.

Neutral white are better - they can be found in 5000k with a "typical CRI" of 80. It's bad that the cool whites are not sorted by kelvins.
Cree LEDs are sorted by bins, where each bin is for a small range of lumen outputs, and by chromaticity, which is roughly the color temperature. A typical Cree LED would be the XR-E Q2 WC, with Q2 being the bin number and WC the chromaticity range. That particular one is the $3 apiece one on DealExtreme and is about a 6500K color temperature.
That's right, but I wouldn't trust DealExtreme specs on the LED. I have contacted Cree distributors and the rule is: the more specific chromaticity you want, the more expensive is the LED. Usually Cree sells reels with a certain lumen output but a lottery for chromaticity.

If I understand correctly, the general consensus is that 6500k is best for a freshwater planted tank ? So I should look for cool white XP-G WC or XP-G "1A 1B 1C 1D" LEDs ?
Look on Ebay, buy 5 metre waterproof LED strip along with transformers. All you have to do it connect the two wire ends which is easy enough with a twist tie and doesn't require any soldering. Stick it to the underside of your hood, plug the transformer into a plug-in-timer, easy, done, cheap.

I'd recommend the 5050 super high-output high-efficiency ones which have 60 diodes per metre (or secondly the 3528), to give you 300 LED diodes per 5m spool. (They're not as high output as CREE's but they also don't run as hot and therefore don't require a heatsink(. A spool with transformer will run you about $60. Some of them are listed at producing 400-450 lumens per metre (or 7 lumens per diode), and consuming 14.4 watts per metre. They're not as bright as Crees, but if it's the same cost and efficiency to use hundreds of these as it is for a few dozen CREE's then that's rather irrelevant.Anyone have any idea how that compares to say 2 florescent watts per gallon though? The 5050's are supposed to last 10,000 hours, and I think I read that they're still producing more than 90% of their rated output after a year, which is far superior to any other type of lights inluding florescent.

I have a combination of warm-white and cool-white on my tank. I prefer the look of the warm-white much better, but have it combined with cool-white for now. I'm not exactly sure which one is better for plants, but having seen the spectral analysis for each, they both seemed to have a decent spectrum to cover the appropriate necessary wavelengths. They had similar light output across most of the spectrum but the cool-whites have an enormous output spike in the bluish range. I'm testing this out on a small tank right now myself, while I'm planning out a larger 200-300 gallon tank. For that tank I know that to achieve 2 watts per gallon, I'd need 5 spools, but as those are LED watts instead of florescent watts that might still be overkill. I had an Ecoxotic Stunner Strip on my small test tank, but took it off as I actually prefer the LED strips I bought myself no Ebay.

The Spectral Graphs for standard warm white and cool white LED's are at this link - http://www.superbrightleds.com/cgi-b...pcool_warm.htm And I'd heard the following:

Plants have two types of chlorophyll: A and B. Chlorophyll A absorbs light at 405 and 640 nm. Chlorophyll B has peak absorptions at 440 and 620 nm. Plant lamps are designed to emit light at red wavelengths to duplicate the light of the sun, but too much red color can cause aquatic plants to grow tall and thin. For best results, use a daylight (5000K) lamp in combination with an actinic white or actinic day lamp.

But I'd also seen statements elsewhere which use slightly different numbers, and it's obviously not as if plants only use a single wavelength of light. I'd also seen 420 mentioned as the peak absorption point for chlorophyll A, and that chlorophyll can use light from 400-550 nm and 650-700 nm. So perhaps we all need to look at this matter a little more closely.

In any case, LED lights do provide some light in the red and blue parts of the spectrum which plants utilize. Personally, in terms of how it made the tank itself look, I prefer warm-white over cool-white, or at least a combination of the two. It would be easy enough as well to add some supplementary bars or strips of red, blue, and/or ultra violet LED's to provide some additional coverage at those points in the spectrum, but you probably would not want to make that the predominant lighting in your aquarium as it might make it look a bit funny. You can inexpensively get 5 metre spools which have alternating red, green, and blue LED's even, and they have some of those that are controlled by remote controls so you should be able turn off the greens if your plants aren't going to use that and if you don't happen to like the look of your plants looking intensely green!

As for myself, I just received my latest supplementary LED lights, which include small wands of Red and Blue, but I'm yet to have a chance to attach them to my hood to see how they look. I'm thinking that perhaps I should have tried to find a wand of ultra-violet as well though.

I'm actually going to be working with a lighting designer shortly to light almost my entire house extension indirectly with warm-white LED's hidden in alcoves, so I'm confident they are up to the task of lighting a tank, if you use enough of them. With each, that would give you 300 individual LED diodes, and it's not as if the photons from LED lighting are different than the photons of any other lights, in contrast to what some had practically suggested elsewhere (in suggesting LED light won't penetrate as deeply).
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Mxx
Been there, done that. Those 5050s are less efficient than XP-Gs, the ebay variety is pure lottery regarding flux and tint and they won't last as long as good quality LEDs.
Those flexible strings are designed for decoration purposes, not for lighting.
So, I guess, it is a no-go with LED lighting until Cree, or somebody else, comes up with high CRI LEDs above 6500K.

Jenya
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