# LED Lighting and Planted tanks



## IWANNAGOFAST (Jan 14, 2008)

I would opt for more of the CREEs running at lower amps. 1500 is going to drive those things extremely hot. maybe go for 15 at 500mA?

But I'm not exactly sure if they can be compared like that.


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## Hoppy (Dec 24, 2005)

One sure way to figure out what LEDs you need is to use a PAR meter to measure the light you get from one LED. If you measure how much PAR that LED gives you at varying distances from the LED, and at varying distances off center from under the LED, and, at varying currents thru the LED, and, if you wish, with various optics installed on the LED, you can determine almost exactly what configuration of LEDs will light your tank to the PAR you want.

Of course first you need to decide on what PAR you want. And, you need access to a PAR meter. Then it is pretty simple. Just follow this method: http://www.plantedtank.net/forums/diy/123797-diy-led-light-45-gallon-tank.html#post1239487 I don't claim this is the only way to do it, nor even the best way, but it does work well.


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## Mxx (Dec 29, 2010)

Hoppy said:


> One sure way to figure out what LEDs you need is to use a PAR meter to measure the light you get from one LED. If you measure how much PAR that LED gives you at varying distances from the LED, and at varying distances off center from under the LED, and, at varying currents thru the LED, and, if you wish, with various optics installed on the LED, you can determine almost exactly what configuration of LEDs will light your tank to the PAR you want.
> 
> Of course first you need to decide on what PAR you want. And, you need access to a PAR meter. Then it is pretty simple. Just follow this method: http://www.plantedtank.net/forums/diy/123797-diy-led-light-45-gallon-tank.html#post1239487 I don't claim this is the only way to do it, nor even the best way, but it does work well.


Are PAR levels an oversimplification of measuring the amount of light for plants though? If plants utilize and need both red and blue light, then PAR measurements don't quite explain whether plants are getting enough of both red and blue, so far as I'm aware. Does anyone have any idea what the right proportion of red to blue light is though?


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## redfishsc (Aug 29, 2010)

shawnhu said:


> There's a few things that I'm still unclear about, and hope someone can help me out here. How many watts/lumens/PAR do I need to power a 10G so that it is equivalent to 4w/g of flourecent? If my calculations are correct, 40 watts of flourecent is about 2400 lumens, which is about 5 of the CREE 3W LED's running at 1500mA, producing ~500 lumens each.
> 
> What color/models of CREE would be best for growing out plants, Neutral White XP-G? Has anyone done the above dimension tanks before that could give me some tips on lumens, PAR, and general layout to achieve 3-4wpg?
> 
> ...



Lumens and PAR don't necessarily convert well, from one to the next. Lumens is more oriented toward light that is visible to the human eye, which is a very different spectrum than light that is active for plants for photosynthesis. 

PAR is a more important number. I don't think it's the end-all, be-all of lighting, but it's pretty useful. 


That being said, 5 XPG over a 10g at 1500mA would probably be overkill unless you use a dimmable driver (a good idea). 

You have other options though, that are slightly more affordable. 

The nicest looking LED to use by itself I have found to be the Bridgelux 402 (sold by Digikey and Newark, just use their search for "Bridgelux"). The cool white 5600K is a very nice LED. At 1,000mA, they are about 8-10 watts. 

You only need to drive them, though, at 700mA and two of them would be entirely enough for 10g tank. 


Option 2-- You can order a pair of 10w "cool white" Satistronics leds (www.satistronics.com), a pair of drivers (one per LED), and a pair of heatsinks--- all for around $60.


The Bridgelux LED is going to be more efficient and probably look nicer, but I currently have a single 10w Satistronics LED over a 10g tank that's growing most plants just fine (just, slower).


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## redfishsc (Aug 29, 2010)

Mxx said:


> Are PAR levels an oversimplification of measuring the amount of light for plants though? If plants utilize and need both red and blue light, then PAR measurements don't quite explain whether plants are getting enough of both red and blue, so far as I'm aware. Does anyone have any idea what the right proportion of red to blue light is though?


I personally suspect, for most of us, in most situations, the ratio of blue to red isn't terribly critical. 

My tanks are drastically more blue than most folks since I'm using LEDs and T5's from my reef tank I took down a while back. 


I grow plants like weeds just fine no matter how much of the white or blue I'm running. 


Personally, I say as long as you have enough intensity (esp. if you can verify it with a PAR meter) then select your lights to please your eyes. The plants generally adapt fairly well.


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## IWANNAGOFAST (Jan 14, 2008)

I don't think plants need as specific a color spectrum as corals do


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## Mxx (Dec 29, 2010)

redfishsc said:


> I personally suspect, for most of us, in most situations, the ratio of blue to red isn't terribly critical.
> 
> My tanks are drastically more blue than most folks since I'm using LEDs and T5's from my reef tank I took down a while back.
> 
> ...


So Redfish has blue tanks? Makes sense to me.


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## Hoppy (Dec 24, 2005)

It is very difficult to hit a PAR value that is in the range you want, without using a PAR meter, and adjusting the height of the light above the tank. Even then, for tanks more than a foot in front to back depth, it is difficult to get that PAR value over most of the substrate without using multiple bulbs or lights. Few people have access to PAR meters, and it will take years, probably, before that changes much. So, it makes no sense to worry about the details of the color spectrum of the light being used as well as the PAR. It did make sense to do that when the problem was finding a way to get enough light in the tank. Back when the only lights widely available were T8 and T12 fluorescents, that was the primary problem, so trying to get bulbs where most of the light was in the "best" wave lengths was a good thing. Today we can easily blast our tanks with 4 times more light than the plants can use, so worrying about using the best spectra is meaningless.


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## sanoshin (May 19, 2010)

For the 10g, just get one of these: http://www.bigalsonline.com/Fish_Li...ndescent_Full-Incandescent-Hoods.html?tc=fish
It has two incandescent bulb sockets, found them for much cheaper at PetSmart.

and put two $1.50 bulbs in it: 
2x 6500k spectrum bulbs you can pick up at Menards / Home Depot - CFL.
Prob would be way more expensive getting LED for a small tank like that, when those bulbs are so cheap .
Thats what I use on my 10g planted shrimp tank, grows great.
I also put 36 cree LED's onto my 75g tank:
http://www.youtube.com/watch?v=1kuSSpnVj2k

Check that post for what i did with my 75g.
http://www.plantedtank.net/forums/lighting/128212-led-diy-light-75g-conclusion.html


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## shawnhu (Jan 23, 2009)

sanoshin, I read your post regarding your 75G build, great thread! Thanks!

I realize that building an LED light for a smaller tank like a 10G, or even a 2.5 would be costly, but like most people here, I'm in the LED for the long haul, so doing my research now to see what's my best options.

I've been studying those charts Hoppy has, but they sure are confusing!


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## Mxx (Dec 29, 2010)

Looking at the colour spectrum of cool white LED's for instance, they seem to provide at least 3 times the amount of blue light as red light, which potentially seems like a lot of imbalance. I found this graph for the spectrum of natural sunlight, which shows approximately equal amounts of red and blue light in the parts of the spectrums where we usually provide those. 










I hear mixed opinions on that, but some aquarists report this makes plants 'leggy', though that may very well be a fallacy. Plants which are accustomed to growing in deep water might expect more blue light as the red gets absorbed in water more quickly, but I suspect most plants we're using were accustomed to growing in shallow marshes and swamps typically very near the surface. And I'm not sure what water depth a 3:1 ratio of blue to red would correspond to.


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## Mxx (Dec 29, 2010)

shawnhu said:


> sanoshin, I read your post regarding your 75G build, great thread! Thanks!
> 
> I realize that building an LED light for a smaller tank like a 10G, or even a 2.5 would be costly, but like most people here, I'm in the LED for the long haul, so doing my research now to see what's my best options.
> 
> I've been studying those charts Hoppy has, but they sure are confusing!


I know I've mentioned this before elsewhere, but if building an LED fixture yourself is cost prohibitive, especially for a smaller tank, then it's certainly easy enough to instead just buy a generic strip off Ebay. You can get a 30" long 72 LED flexible strip for the princely sum of... $1. With shipping it's $4 total, and you'll need a $2 12V transformer plug and the ability to twist to wires together to hook it up. That is what I've been using on my nano Edge and it works perfectly well and provide a lot of good quality light. For a 10 gallon you could get two strips like that if you want to really splurge. Should you not like it then you haven't exactly broken the bank I'd hope. 

(P.S. I'd personally recommend one strip of warm white combined with one strip of cool-white for best appearance).


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## sanoshin (May 19, 2010)

If you have never seen this website, I enjoy the wide variety of information on it:
http://www.americanaquariumproducts.com/Aquarium_Lighting.html

They have tons more info at the top, under aquatic information.

But they post a picture about half way down that page, under the LED section, which shows why most hydroponic green houses use LED's now. The par is nearly matching that of what is needed for chloryphil.

Good stuff!


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## Zareth (Dec 13, 2010)

Use equal parts Red Green and Blue LED's  
You'll make white light and you can fine tune the spectra and the way it will appear to you by putting each bank of LED's on their own variable resistor that modifies voltage. 
http://hacknmod.com/video/massive-500-led-extreme-flashlight/ check out this DIY for a flashlight for some ideas. 
I'm more of a fan of using a higher number of regular LEDS as high wattage LEDS are inefficient and hot. You wont get as much of a flicker effect but you'll get better light distribution and if you use the variable resistors you can fine tune for any color.

But I just read that above link and maybe it'd be okay to just skip green leds all together


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## Zareth (Dec 13, 2010)

.. I need leds


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## Hoppy (Dec 24, 2005)

Mxx said:


> Looking at the colour spectrum of cool white LED's for instance, they seem to provide at least 3 times the amount of blue light as red light, which potentially seems like a lot of imbalance. I found this graph for the spectrum of natural sunlight, which shows approximately equal amounts of red and blue light in the parts of the spectrums where we usually provide those.
> 
> 
> 
> ...


The problem with that chart of natural sunllight is that the spectral distribution changes during the day. The changes are not small. Early mornings and late afternoons, the spectrum includes far more red vs blue than at noon in full sun. And on hazy or cloudy days the spectrum is different from on clear days. At higher altitudes the spectrum is different than at sea level. And in the shade of green foliage the spectrum is different from that under the open sky. The one very consistent thing is that in all cases the light intensity is the same at the water surface as at the substrate level, something we have a hard time even coming close to.


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## Mxx (Dec 29, 2010)

Thanks sanoshin, I'd seen that website previously and should have referred myself back to it to read more closely. So it appears based upon that, that plants actually use 20-30% more red light than blue light, which would correspond much more closely with the output by warm white LEDs. 

Zareth - Trying to be clever I ordered an RGB LED strip myself to experiment with. I wasn't able to use it unfortunately, as after receiving it I realized it was a few mm wider than other strips and therefore didn't fit in my very minimal profile DIY LED fixture... I put the strip on my tank to see how it looked, but it didn't look great. It had poor colour rendition and looked very cold and blue actually. I'm not sure if the Blue diodes have a greater light output than the red, or if our eyes are less sensitive to the red of that wavelength. It might have worked well for the plants, but I'd rather prefer to have lighting which looks good instead.


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## Zareth (Dec 13, 2010)

Mxx said:


> Thanks sanoshin, I'd seen that website previously and should have referred myself back to it to read more closely. So it appears based upon that, that plants actually use 20-30% more red light than blue light, which would correspond much more closely with the output by warm white LEDs.
> 
> Zareth - Trying to be clever I ordered an RGB LED strip myself to experiment with. I wasn't able to use it unfortunately, as after receiving it I realized it was a few mm wider than other strips and therefore didn't fit in my very minimal profile DIY LED fixture... I put the strip on my tank to see how it looked, but it didn't look great. It had poor colour rendition and looked very cold and blue actually. I'm not sure if the Blue diodes have a greater light output than the red, or if our eyes are less sensitive to the red of that wavelength. It might have worked well for the plants, but I'd rather prefer to have lighting which looks good instead.


Yeah that website that sanoshin linked to said that many of these LED light fixtures look dimmer to us because they lack the green/yellow wavelengths of light, but they are actually much more useful/brighter as far as plants are concerned


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