LED Tank Lighting Experiment with 1st look at results...

Those high-powered LEDs are so fantastically bright, their strength looks like sunlight to my eyes! It makes me giddy to think that this could be a cheaper solution to the difficulties of growing really high-light requirement plants like Cabomba furcata, warmer water strains of Podostemum ceratophyllum, a lot of the Potamogetons or giving normal Ludwigia palustris and repens eye-popping red colors... More dream-aquarium fuel for me! Thank you for publishing your expirement!

Those high-powered LEDs are so fantastically bright, their strength looks like sunlight to my eyes!

There is also sunlight shining upon the tank in post #80. Look at the the reflection of camera and hands on the glass. This would not happen if the light was solely coming from inside the aquarium.

Usil, can you take new photos at night time where the only light turned on in the room is the LED that you're referring to? That would give Orangespotted a better idea of the illuminating strength of your light. Thank you

Edited by EricaWieser, 29 December 2011 - 10:19 PM.

Those high-powered LEDs are so fantastically bright, their strength looks like sunlight to my eyes!

Haha, I'm pretty sure that what you are seeing in those photos is indeed sunlight.

I also am having a ton of filamentous algae growing quickly in a small tank that sits in the window at work. I've had sunlight tanks before never with algae problems, but in this tank I am constantly fighting the algae.

Edit: Well, I see Erica already commented on the sunlight subject. And, yes, a photo at nighttime would be great for us to actually see the tank lights. Thanks!

Edited by UncleWillie, 29 December 2011 - 10:20 PM.

Yes, Erica is right, in these pictures I took them in the morning with sunlight coming into the window. It was not for light comparison but to show plant growth for these two pictures. I will take a few more at night to better compare to the other night shots I have made using just the LED lights for the shots. I will try to get these posted in by this weekend. However, as I have already taken pictures using just the LED lights (see post #71) it will look the same as those.

Usil

Edited by Usil, 30 December 2011 - 12:05 AM.

Usil, your aquarium is beautiful. I have LED lights on two of my three aquariums, and I will be switching the third soon. I am not doing the science as thoroughly as you, but my plants are doing great and I love the idea of reducing our energy use. My family is working on reducing our "footprint" on the planet and every bit helps. As long as the fish are healthy, plants grow well and the aquaria are attractive, that's enough for me.

Thanks, your research has been very helpful.

Thank you Usil for your excellent experiments. I have been following this thread since its beginning.

Based on your experiment, I decided to see what I could find at the local hardware stores. I purchased a 4 light LED light bar (Utilitech model GUO124L-SS-I) for $40 from my local Lowes. It is a 4 LED light bar "suitable for damp locations". These fixtures are linkable to additional fixtures, up to 60 fixtures in series total. They are rated at 0.09A max each.

Output is rated at 310 lumens, bright white. Color temperature is 3000.0 kelvins. Color rendering index is 80.0 kelvins. It is rated for 50,000 hours. Maximum fixture wattage is 7.0

I used 8 pieces of scrap glass pane to make spacers to go between the top of the tank top and the light bar to allow for sufficient air flow to remove heat and to keep the fixture from any puddling of water on the top of the tank lid (shown in photo). These pieces of glass were perhaps 1/2 inch in width and sufficiently long to span the width of the fixture and were glued together in two stacks. The fixture is rested on top of these two stacks of glass and placed on a 20 gallon aquarium.

As you can see from the photo attached, this provides a large amount of light for this 20 gallon aquaria. They do produce a 3 LED fixture also, as well as a 5 LED fixture. I purchased the 4 LED fixture as I intend to use it on my 90 gallon tall and wanted to see how well it worked while building my stand for the 90. I am also impressed by the light weight of the fixture. I think the box it came in weighed more than the fixture does.

 IMG_01741.JPG   1.14MB   3 downloads

Erica, based on the color temperature and CRI, can you tell me how effective this lighting would be for plants?

This product is rated for use in damp locations. If used in wet locations, it is probably desirable to use a GFI outlet or GFI power strip to protect yourself as this is not an actual aquarium use product.

This has been a real informative thread since it has inspired me to buy a cheap LED strip and experiment on developing my own LED light for my smaller tanks.

Pictures and information will hopefully be forthcoming, time permitting of course...

Scott

I purchased a 4 light LED light bar (Utilitech model GUO124L-SS-I) for $40 from my local Lowes. It is a 4 LED light bar "suitable for damp locations". These fixtures are linkable to additional fixtures, up to 60 fixtures in series total. They are rated at 0.09A max each....Output is rated at 310 lumens, bright white. Color temperature is 3000.0 kelvins. Color rendering index is 80.0 kelvins. It is rated for 50,000 hours. Maximum fixture wattage is 7.0

...

Erica, based on the color temperature and CRI, can you tell me how effective this lighting would be for plants?

Without the spectrum it's really hard to say. I looked it up on the Lowes webpage but it didn't say the spectrum, either. Under color it just says "soft white".

When you are buying a light for plants, the one thing you really want to look for is its spectrum. Here is the absorption spectrum of chlorophyll: http://upload.wikime...ab_spectra2.PNG If you look at that image, you'll notice that the region from 500 to 600 nanometers has a near zero value. That means that no matter how bright the light is, chlorophyll can't use any of the energy from that region. And you can't know the spectrum of a light just by looking at the light's color. If you'll allow me to make an analogy, white light is kind of like the number 10. There are a lot of different wavelength combinations that add up to ten. 4 and 6 add up to 10. 2 and 8 add up to 10. 5 and 5 add up to 10. If your plant can only absorb energy that is 4 or 6 and none of the energy that is 5, and if your light is only producing 5 type energy, then your plant absorbs zero energy from that light. The 3,000 degrees Kelvin that you described is the color of your light. It has nothing to do with its spectrum. This picture might help you visualize it: http://upload.wikime...-comparison.png

If you use a spectrometer to tell what the spectrum of your light is, then I can tell you if it's good for plants. My old digital camera had a spectrometer in it as a toggle-able display setting on the screen. Using a digital camera is a cheap way to find out. You can also use a prism or a diffraction grating or even a bowl of water and a mirror to split the light into its component bands. Here's an example of a super cheap way: http://www.weirdscie...htSpectrum.html specifically http://www.weirdscie...ed5-350x200.png

Edited by EricaWieser, 30 December 2011 - 05:17 PM.

Thank you Erica.

I read this shortly after your last posting, but having no spectrometer or prism, I decided to give the tank some time to develop. The tank is now supporting algal growth on the rocks and glass. I don't know the intensity of the spectral bands. Perhaps I will try some coontail in the near future and see if the lighting will support it.  IMG_01811.JPG   1.21MB   1 downloads

Edited by LincolnUMike, 26 January 2012 - 12:54 PM.

And you can't know the spectrum of a light just by looking at the light's color.

I found this a few months ago:

However there IS a relationship between a colour temperature and the peak wavelength in its spectrum. It's called Wien's law.

Wavelength (nanometers) = 3,000,000 / Col temp (Kelvin).

I found it here: http://www.cinematog...nConversion.htm

In some other places I also saw 2,900,000 used, but either one is probably close enough as like you've stated, you can't get an exact conversion, but this may be close enough to get in the right direction. I used it for determining the bulb temperature for my T8 fixtures. I use one 5000K bulb and one 6500K bulb. If you do the math it, it gets pretty close to both wavelength ranges that plants use.

I am certainly not an expert in this field, so this information may be totally worthless, but it seems to be working well for me so far.

Steve.

Peak wavelength is information, yes. But is it enough information? no.

Take a look at this image: http://bruce.cs.cf.a...7/LA_137(b).jpg
On the upper left you can see that ambient, full spectrum light like the sun has nonzero values all across all of the wavelengths for the entire spectrum. On the upper right is shown a lamp, where yes, there is technically a peak wavelength that is taller than the other two nonzero wavelengths. But does where the peak wavelength is located tell you anything else about spread of wavelengths being emitted from the light? No, it doesn't. How much of that light is present at other wavelength values? It's impossible to say. Heck, the light could even look like the one on the bottom left of the above image, where the peak wavelength is really all there is to that light. A good light needs more than just a single strong peak; it needs high energy values at a wide range of wavelengths, specifically those in the 400-500 and 600-700 range.

Here's another image: http://www.olympusmi...rcesfigure3.jpg
Noon sunlight has high energy at nearly every wavelength. That particular mercury vapor lamp, although it does have two peaks in the 400-500 nanometer region, lacks quite a lot of energy when compared to sunlight. Both lights look white. Both lights have max peaks within a hundred ish nanometers in wavelength. But the two lights are completely different for growing aquatic plants.

Spectrometers/diffractometers aren't expensive. It's like $4 for a diffraction grating. Here is an example grating for 95 cents: http://www.onlinesci...-in-2x2-in.html I got a shipping estimate from them and it's just shy of $10 to get that diffraction grate shipped to my door. Maybe that's too much to pay for shipping compared to the cost of the product, but you get the idea. Diffraction gratings are cheap. Even I, lowly graduate student, could afford one. *looks at product more closely* and might buy it... useful...
Edit: $5 diffraction grating, including shipping. Link: http://www.ebay.com/...=item3f0e1539ba

Edited by EricaWieser, 01 February 2012 - 03:02 PM.

Also, I found this handy video that shows you how to use your diffraction grating once you get it.

Edited by EricaWieser, 01 February 2012 - 03:12 PM.

The answer to the question of whether it will work is locked into the frequencies emitted by the LED emitters. If we trust the manufacturers description and we see "FULL SPECTRUM" listed in it's description then we know that this will contain the plant light frequencies (PAR light spectrum) which is contained within the 'FULL SPECTRUM" of any bulb or light. If we don't trust the description like Erica said, a very cheep holographic diffraction grating will show you if it contains the entire visible spectrum or not.

The next issue is will it have enough power to reach the bottom of the aquarium. My tables show that there is fall off so get the strongest LED lights you can manage. Just note that those LED's that are listed at 1 watt or more will require a heat sink. Those under should operate fine without one. Under 1 watt each should operate fine with a cheap Radioshack power supply that provides the volts necessary for the LEDs at about 750 milliamps dlivered power. Over 1 watt requires a power supply like I used in my project.

Usil

Erica, I agree with what you are saying, and I'm certainly not trying to discourage anyone from using Spectrometers/diffractometers, as this is undoubtedly the best way to find wavelengths. I'm not even trying to take a disagreeable stand on this. I'm only saying that there is some limited correlation and it can have some limited use. If the peak wavelengths are in the right places it can work well. With my set up I've recently been cutting back on my lighting because the growth is literally just more than I can stand, but this is an LED thread so I won't go into that any further. Anyway, I just wanted to add the information as a quick help. Sorry for the confusion and thanks for the clarification.

Steve.

Usil you should come to a DFW Planted Tank Meeting. This would be a great topic for discussion.

I would not mind talking about this but i am not a member.

Usil

I would like to revive this topic I was wondering if there have been any updates on the LEDs I'm planning on building a canopy for my 125gal and I was inspired to do a DIY LED system for a 6ft long aquarium. Any advice you guys can share?

The system I built and reported here step by step is still up and running fine. Materials I used are all working perfectly.

Usil

One thing which has definitely changed is the availability of reasonably priced commercial alternatives to the high power set ups. Diy still offers many advantages, but the price gap between diy and commercial has narrowed considerably. Three reef quality fixtures which will cover your tank and which you'll probably have to dim down can be had for less than $400 shipped to your door. All you'd have to do is hang them, plug them in and set the dimmers. Diy for its own sake is always cool, but if finances are a major part of the consideration......

I would like something cheap and DIY