# LED configuration and the ideal spectrum.



## Chiefa

I have been reading up on LED lighting for reef tanks and the success people seem to be having.
LEDs can penetrate deep, give the shimmer effect, run cooler (active fans), don’t heat up the tank water and cause less evaporation (possibly more efficient, but I’m not touching that one) so I am wondering why hasn’t it taken off in the planted aquarium?

The main Issues, I find, are the cost of the lights and the spectrum that they put out. (Depending on type of LED)
I’m trying to learn about spectrum and PAR at the moment and from what I understand, plants utilise more of the red and blue spectrum and less of green and yellow.

I may be able to get a manufacture to configure an LED light with 119 LED's (120w) with various mixes of blues/reds/whites, fully customisable.

My question is, would it be beneficial for the plants to have a few red and blue LED’s, mixed into different whites (daylight/cool white/midday) in an LED panel?

If cost wasn’t an issue and you could choose the ideal spectrum for the LED’s what type of mix would you go for?

For example. - 
15% red led @ what spectrum or range
15% blue led @ what spectrum or range
70% white led @ what spectrum or range
or,
20% red led @ what spectrum or range
20% blue led @ what spectrum or range
60% white led @ what spectrum or range

I’m just wondering what the perfect spectrum would be for plant growth, and bright enough for me to look at.


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## ianryeng

You are missing a few critical pieces of information

1. What size tank are you building this for? (LxWxH)

2. For what reason have you elected to use 1W vs 3W LED's
- there is some evidence to suggest that while the increase in lumen is trivial the increase in par values is not. As such you are probably better off running at 1A vs 350mA and will be able to utilize less emitters​
Assuming you are going to utilize 6500K led's you would probably be better off with the 70-15-15 mix only because the cool white and blue range of led's are far more advanced than the red and other spectrums. So you will get more par/watt this way. The cool whites on their own should be adequate for growing and to my knowledge you would be best off with something more like a 90-10 or 80-20 mix of cool white (6500k) and red respectively since blue is mostly for direction of growth.

For example for a refugium light on my reef setup I am using 8 cool white and 2 red as there is plenty of blue in the cool white emitter.

Stick with Cree (XR-E or XP-_ series) as they are very good emitters with a proven reputation in the aquarium industry.

I know I have seen a few diy planted tank builds around. I cannot explain however why there are not as many planted tanks with led than reef tanks. I would imagine everyone would benefit from being able to adjust their colour temp to their liking.

Good luck with the project, let me know if you have any other questions and I will try and help you out.

-Ian


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## jestep

The problem that I've seen relating to your research is this.

The best LED's have an efficiency of roughly 70 lumens per watt. Most 1w led's are 20 - 50 lumens. With a 120w (1w /led) setup, you would have 8400 lumens (best scenario) and most likely ~3000 lumens.

Compare the cost of t5 lighting, for 3000 lumens you're looking at a cost of about $15, whereas the LED's are going to cost hundreds before you get to the drivers. The life is a good argument, but the payback in the best case scenario isn't for about 10 - 15 years.

As far as spectrum goes, LED's with a reliable spectrum in either 1w or 3w, are very expensive. Anywhere from about $3 - $10 per LED. You would ideally want from 5000K to 8000K color spectrum, which is generally the warm and cool white LED colors by name. Blue, red, even plain white, or anything else is way out of usable spectrum.


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## Im2Nelson4u

Cree Q5 put out 107 lumens at 350ma and cost about $4 per LED. A 48W driver cost about $30 and will power 13 of those Q5s... 

Assuming you run them at 1amp you will get 3900 lumens per 13 LED setup which will cost you about $100. Seems to cost a bit much but then again you don't have to replace the LEDS for atleast 10+ years.

You should read more about PAR since thats is what is important not lumens.


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## ianryeng

I concur and will reiterate 

The par output while less documented is considerably higher with 3W (1A) led's which is what you are interested in. Lumen is just a representation of how we see light, not plants.


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## Chiefa

Thanks guys for your info

_Ianryeng_, I will be placing the light over a new 4x2x2 setup.

The reason im going LED is, I purchased the Aquaone MG1200 2x150wMH 4x24wPC. $220aud from a friend. 
See link: http://www.aquaticplantcentral.com/forumapc/lighting/68130-metal-halide-vs-t5-s.html
I was happy with the light; however I started becoming uncomfortable with the heat it was putting out and the size of the unit. 
To buy fans and to replace all the bulbs would have cost me around the $200aud mark. So the light quickly became a $440aud light. Also I couldn't use the hood I wanted.

During the course of researching, it soon became apparent that the regime involved in keeping a 4wpg tank would be significant. ( I didn't have a clear picture of what I had wanted and rushed into it) So i sold the light without purchasing anything extra.

Moral of the story research, research and research

I can get the LED units for cheap and customized. I figure I can skip the T5's as I have nothing now, and go with LED lighting that provides plenty of benefits. (No replacement bulbs, cooler, smaller, provide shimmer etc...)

After more reading, I realize I may have been asking the wrong questions... kinda
So this is what I have come up with.

A ratio of 2to1 red650nm, blue450nm and the rest white 8000k or 10000k or mixed
Im not sure about the whites, i do like a bright tank.

30 red
15 blue
74 white

Anybody have any opinions on what would be a good ratio?


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## Im2Nelson4u

Your still going to need fans and a heatsink to cool those LEDs...


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## Chiefa

Im2Nelson4u said:


> Your still going to need fans and a heatsink to cool those LEDs...


Sorry should have explained, these units come with heat sinks and three built in fans.

Here are the specs:

1w high power leds x 119pcs 
120 degree wide beam angle 
L40cm x w21.3 x 7.1cm 
Gross weight : 5kg 
3 x Quiet Power Fans

Here are some pics:


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## Im2Nelson4u

WHOA 119 LEDS and here I was complaining about mounting 13 leds lol...


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## ianryeng

I would be concerned that 1W led's would not get the par values or depth penetration that you need/want. Is the brightness adjustable on this unit? I would imagine you would want independent control of the different coloured emitters.

what is your plan for the layout of the led's based on the dimensions you have stated and the ratio and # of leds desired?


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## jestep

ianryeng said:


> I would be concerned that 1W led's would not get the par values or depth penetration that you need/want. Is the brightness adjustable on this unit? I would imagine you would want independent control of the different coloured emitters.
> 
> what is your plan for the layout of the led's based on the dimensions you have stated and the ratio and # of leds desired?


The actual output would be relational to how they are wired. If they are wired for 1000mA instead of 350mA at the same voltage, they will be 3W and not 1W. If you wanted dimming control and the ability to push them up to 1000mA, you would need to wire them for 1000mA using a dimmer or a dimming driver.

The rating on the Cree's is as follows:
350mA: 107~114lm
700mA: 171.2~182.4lm
1000mA: 214 ~ 228lm

You get more output at the higher current, but less efficiency (lm/W). The drawback is that these are expensive LED's, each one costing over $5. More current means less LED's per driver, and more drivers for the same number of LED's at 350mA. It's definitely a push-pull as to what is going to be the most efficient and cost effective.


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## ianryeng

1. Voltage is irrelevant to diodes, they need current and as a result of that current they absorb voltage.
The wiring for 1A is the same as 350mA, it is just a matter of what driver you are using.

2. Dimming control has nothing to do with what maximum current you choose to drive them at (1A or 350mA). Ideal would be having the full range of your diodes available (whether it be 0-700mA or 0-1A) as long as you do not exceed their rating. The dimming itself is achieved through PWM the current source limiting the current available to the diode.

3. LUMEN IS IRRELEVANT. Plants ONLY care about PAR. Cree does not provide PAR data. However, there is a great deal of data available to suggest that the PAR values are considerably higher when the emitters are driven at 3W opposed to 1W. You need the penetrating power, especially with a 2' deep tank. You cannot relate the lumen data to par data as they are completely different measures.


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## Chiefa

Thanks ianryeng,
I have thought about the ratio will be and have come up with the following.
Please offer any suggestions/comments.

Blue450nm x 14
Red652nm x 33
White 8000k x 60
White 10000k x 12

I dont know if the LED's are being driven at 350mA or 1A, no you cant adjust the brightness. 
Unfortunately I cant give you PAR readings, but have had reports of 330lux per watt??? 
I have spoken to a few people that have them for both planted and marine and they stated that the light does penetrate quite well.


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## ianryeng

As long as you are fairly confident that it will be bright enough. You can always raise a fixture to reduce the concentration but you can only lower it so far 

The ratio of led's may be ok but I personally would have more in the white range say ~100 and maybe a 2:1 red:blue for the remainder (so about 13 red 6 blue). It really depends on what the led's are though. Ideally the ratio you have posted should work great as long as they are all comparable in output (some led's are more developed than others)

I would be more inclined to recommend replacing the 8000k and 10000k with 6500k and something in the 3xxxk range. Not only are these colour temps typically more common and therefore cheaper they are closer to what your plants should like.

The 6500's have a fair amount of blue in them to start with (which is the complaint I hear commonly from people using them in flashlights) and the 10000k have very little red spectrum.

You can check out some threads around here to find out what other people are doing;
LED Experiment Tank

What's the skinny on LED Lighting

In terms of the lux rating is that per led? Here is some comparative data on lux, they are not much more useful to us than lumen to be honest. All it tells us is what it will look like to us

100 lux Very dark overcast day
320-500 lux Office lighting
400 lux Sunrise or sunset on a clear day.
1,000 lux Overcast day; typical TV studio lighting
10,000-25,000 lux Full daylight (not direct sun)
32,000-130,000 lux Direct sunlight

(Wiki)

In the end there is probably no perfect solution. I like the sounds of what you have so far but would definitely consider changing your white colour temp (either all 6500k or a mix) and maybe adjust your ratio's.

I hope it turns out great!


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## Im2Nelson4u

Have you thought of using the new Cree XP-G? 

345 lumens at 1 amp and best of all ! 3.2V !

about $6 per LED


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## ianryeng

The XP-_ series led's are definitely an improvement over the XR-E series in terms of visible output. Their current disadvantages are that they are available with a maximum of 40 degree secondary optics (where for the XR series you can easily find 60 and 80 as well). What this means is that you would have to have a fairly dense array to eliminate spotlighting or raise the fixture fairly high over the tank to achieve the same effect.

They are indeed great looking on paper and hope that it translates to people having great experiences with them in the community. I just don't see them as a great option on the planted tank side yet as I would imagine you would not want anything sharper than a 60 degree optic (probably 80 would be better) for this type of application.

If anyone has experience with the XP series on planted tanks I would be interested to hear


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