LED to replace light source for planted aquarium.

[ctlam]

Hi,

Do anyone know whether is it possible to replace any light source using only LED?

What colour of LED is required for planted aquarium? Both the LED and light tube have different measurement for brightness and etc. How to link them together?

Anyone out there try this before?

Regards
Lam

[FC]

Hi Lam,

"Do anyone know whether is it possible to replace any light source using only LED?"
Yes, obviously.

"What colour of LED is required for planted aquarium? Both the LED and light tube have different measurement for brightness and etc. How to link them together?"
I do not have the information on the latest white light LED. However, LED is not an ideal source of light for planted tank or lighting up decorative items because it is not built to duplicate the natural (sun) light. Technically, it means that lited items's colours will be distorted/not true colour. Even if one can find LED (light spectrum) that can grow the plant, they will not look nice under such light.

LEDd is energy efficient and low heat but they are tasked to do indicative/alert functions and lately emergency light (hand torch, car interior light like Nissan Latio).

[hwchoy]

technically you can use LED, especially those ultra bright ones. however as Freddy noted, the spectrum may not match the requirement for growing plants. for that matter normal FL/PL tubes are not that ideal too as plants requirements specific peaks in parts of the red and green spectrum (I think, and you should do some research there i.e. google)

you can check out the websites of the various LED manufacturers (google for "super bright LED") they do list the spectral characteristics of their LEDs. what you might do is to make a combination lamp using varying ratios of white, red and green LEDs. I actually toyed with the idea of putting in some UV LED which I believe enhances the colour of fishes.

one thing you should note is the penetrative power of LED lights. it may not be intense enough to reach the bottom of the water column where the plants live.

not to forget, by the time you rig up enough LED to match the lumens of PL light, it is probably going to be quite expensive.

[SnyperP]

It's more than possible. Gomer did a test with Luxeon Stars vs PC lighting about a year ago.

http://www.aquaticplantcentral.com/f...ghlight=luxeon

Is it cost effective? No, those luxeons are quite expensive =D

[stormhawk]

Lam, there's a particular thread in this subforum posted ages ago by one of our members from Poland. In it he detailed his construction stages and how he wired up the LEDs to the wiring for the lighting.

If I recall correctly, he uses PL (compact fluorescent) lights during "dayling" hours and utilises the LEDs (blue I think) as a night-light feature. A search with the term LED should throw up some previous discussions.

[ctlam]

Hi All,

It is very interesting to know that there are people to do the experiment. It seems like LED can have some advantage over the PC light. Only thing is LED can be more expensive but over long run LED will be cheaper.

If I were to used the LED to replace the tube, do I only used super bright White light or must mix with other colour such as red, green or blue?

Regards
Lam

[primavera]

IMHO, I dont think you need to mix it with other colours, just use the brightest white LED you can find.

I remember reading a website on fluorescents that say the colour/type of light does not really matter, as long as it is bright white. Plants can use whatever photons that fall on their leaves. Although red and blue are the prefered spectrum, the website noted that Amano uses more green with good success. As most aquatic biotopes have some form of overhead shading, he reasons most of the light that goes through would be in the green range.

I personally have not tried LEDs, just using screw in compact fluorescents around the 20 W range over my small tanks. I would think LEDs are more suited to extremely nano tanks. Maybe even a vase type tank or a glass tumbler with moss only...how cool. As noted by hwchoy, it has low penetrance. If I have access to it, I would definitely try it out.
Benefits are:
-small, fits into awkward spaces for 'novelty' tanks.
-low heat, doesn't heat up especially small bodies of water.
-Economical energy usage
-can play around with different colours, maybe do a disco tank! ...

Regards

Min

[hwchoy]

Plants can use whatever photons that fall on their leaves. Although red and blue are the prefered spectrum,…

by way of a quick reply since I'm relying on memory here. the photosynthesis process is driven by two specific ranges of colour spectrum (I think in the red and green range) and in order for the plants to effectively use the light energy they must be within those ranges. Lights of other frequency will still impart some energy to the photosynthesis pathway but much less efficient.

This is the reason some set up mixes red and green LED that exhibits high output at the required spectral ranges. You need to check the spectrum of the LED you intend to use to ensure a good spread over the spectral range.

[Scott_sg]

Hi,
The energy of a photon is proportional to the frequency, and different pigments will absorb better at certain frequencies. So in general the spectrum will make a difference.
Most domestic light sources are good for humans to see but not always for plants. Most of the special tubes for plants, reef etc are optimised for plants. It is really more about efficiency, a specialist plant tube will emit more energy that can be absorbed by the plant than an equivalent domestic tube.
Incidentally red is absorbed very fast by water, all red is gone by about 5m, that is why most plant tubes are more in the reddish wavelengths. (Also why water has such good thermal capacity to get technical.) Blue penetrates the deepest - also why you can still get sunburnt scuba diving.
I have to agree though i like the screw in fluorecents, but then again all i grow is java moss and a poor excuse of an orchid at the front door.

Scott.

[whuntley]

Plant action spectra (growth vs spectral light content) has been measured a lot for non-aquatic plants. Little study has been devoted to the aquatic species, except algae.

Aquatic plants still use the same chlorophylls for photosynthesis, so the action spectra peaks in the red and deep blue are no doubt pretty much the same.

The A and B chlorophyll have broad spectra that overlap in the center of the visible spectrum, where our eyes are most sensitive. That overlap is a huge dip in their growth curve, though. The strong peaks in blue and red, where out eye's visual sensitivity and acuity are worst, are where our sensitivity is down to about 10% of what we sense in green. [Note that many if not most plants reflect away the green light they don't use efficiently.]

Amano's use of green has little or nothing to do with photosynthesis. It is a color that you, as a human, can focus on better and see as brighter. Period.

Red, by the way, is not "all gone" at 5M depth. At 3M, about 44% has been absorbed, so most observers see a definite blue tint. <http://www.dartmouth.edu/~etrnsfer/water.htm> A 3M-deep swimming pool made with white plaster will look quite bluish from the 6M of round-trip transmission, but there is still lots of remaining red so that it is a very pastel blue, not a deep color at all.

[The color of water in a white bucket was a raging thread for months on the Aquatic Plants Digest. It is still a favorite "in" joke, there.]

In any reasonable tank depth, the loss of red is totally negligible, so forget that old myth. Light loss with depth is due to shadowing of higher-up plants. Any light entering the undisturbed surface of a bare tank is totally internally reflected by clean tank walls, so at 1M depth, a light meter will see virtually no loss (less than 2%, probably).

For an aquarium, we need all of the spectrum. The red and blue ends of the spectrum contribute considerably more to photosynthesis, but the central green is needed to make it look bright and sharp to our eyes.

We also don't focus as well in the spectral ends, because we suffer about 1/8 diopter of chromatic aberration in a normal eye. We are so accustomed to red and blue not being in good focus that we tend to ignore it. [Display designers ignore it at their peril!]

It is more likely to produce good illumination if you use red, green and blue LEDs to get the kind of white you find pleasing and still enough red and blue for good photosynthesis. The "white" LEDs are usually blue with a phosphor, and they will give you no spectral control, like mixing RGB LEDs will. Overall, I suspect they are less efficient, too.

An LED is a non-linear device that is current activated. It is a serious mistake to use a Voltage supply to drive them, for you must then use a resistor (wasting energy) to limit the current. Plan to use a high-impedance driver circuit for each LED, if you don't want to add unneeded heat to the tank.

Wright

[Scott_sg]

Hi,

Throwing in 2.618 cents worth here again, but red light of approximately 700nm has a loss of about 28% per meter. That is for pure water so it is often much worse for fresh water, marine waters differ again. The wavelength absorbed also depends not only on the HO bonds but also on Hydrogen bonds, so the absorption will jump across the spectrum. That does not also include the normal sediments of freshwater.
This all comes about from Lamberts law which is derived from the radiative transfer equation. Eventually all the Light is absorbed as thermal energy. Thats the Physics of it anyway.
From a plant point of view more red could only be in general good, but again that would depend on the type of plants and the intensity of light they require. Red plants due to the caratenoids will benefit from some green also. Chlorophyll a mainly absorbs light at two wavelengths: 440 nm (blue-violet) and 670 nm (red), and that is the main ingredient of photosynthesis.
The human eye is most sensitive between 500 and 600nm so it is always a problem of what is good for our eyes and good for plants, or in some cases animals.
For LED's in general the ones we would call white are really blue (Phosphor), and most of their spectrum is in this range. About 450nm, and they will move towards yellow with time, so like fluorescent tubes, they would have to be replaced as they age. And Wright is right again, they are very current sensitive, and it is easy to mess them up, 20mA or so for max ratings i think.
If i had more time i would play around with it, since i think that with some thought using the LED's could make for some very nice setups.

Scott.

[hwchoy]

also I am of the opinion that some UV is good for the fishes. how else to explain what fishes reared out doors have such strong colours (even not under direct sun) and higher growth.

can consider mixing some UV LEDs.

[Scott_sg]

The problem with the UV is some is absorbed very fast. And the ones that penetrate water well, also penetrate tissue well.
But it is a great steriliser, so it does help keep bacteria and things in check.

I don't know about fish but definitely lots of animals need sunlight, even humans we need it to make vitamin D in our skin. That is why after a day at the beach for fair skinned people that sleepy feeling comes on, your body has made excess vitamin D, so essentially we have to sleep it off. Although all the running around and play is a big part i imagine.

For the colours i think that is probably due to more varied food in the wild and ponds. They have a lot more variety and can pick up more natural pigments from all the different things they eat. That is why wild fish also taste better

Now I think about it the UV ones could be useful in moderation for tanks with disease, or even to prepare water for hatching or anything you want really clean water for. But you would have to make sure the water has a high turn over and also that you don't damage yourself or your fish with them.

Maybe it would be a good basis for a DIY UV steriliser, since the ones in the shops cost a fortune for the marine people, but for just occasional use it would be cheap and easy to rig something up,

Scott.

[timebomb]

I know little about UV and all but many years ago when I kept many types of Goldfish, I know they will lose their colour if I bring them indoors. In my balcony tanks which are exposed to sunlight, the gold in the fish shines. The Black Moors become all black, like charcoal. When I bring them into the tanks in my living room, the colours fade and the Black Moors turn white at their bellies. If I bring them out, they turn all black again.

Loh K L

[BeyondGomer]

The problem with the UV is some is absorbed very fast. And the ones that penetrate water well, also penetrate tissue well.
But it is a great steriliser, so it does help keep bacteria and things in check.

Water doesn't begin to absorbe UV till below 200nm. 200-300nm is on the harmfull side. If you want to suppliment, you will want to use 300-400nm which is what we are exposed to (O3 cuts off UV in the atmosphere at ~<290nm)

[Scott_sg]

Thanks Tony, I have to admit my knowledge of UV is going back 15 years so it was a bit blurry, but good to see some hard numbers.
KL you mentioned something very good, I know exactly what you mean about the black moors, (even longer since I played with them though) but definitely the ones from a pond get a real rich black, while in low light they get that bronze colour in them. Obviously it is melanin in this case, but still an excellent example of sunlight directly helping to colour the fish. I also remember fish kept in the dark will really fade, even neon tetras will become almost white given time. We used to keep them in the dark for spawning, but not sure how it is done now. Anyway when I think about it more, yes definitely light must influence the strong colours, although I am not sure how.

Scott

[RonWill]

Water doesn't begin to absorbe UV till below 200nm. 200-300nm is on the harmfull side. If you want to suppliment, you will want to use 300-400nm which is what we are exposed to (O3 cuts off UV in the atmosphere at ~<290nm)

Tony, could you elaborate further but in layman's lingo? I suppose this 'nm' is the wavelength and if so, at which range would it be lethal to bacteria and stuff, that passes through a UV unit? Many thanks.

As for LED lights, I've seen those torch light fitted with 19 bulbs. Bright as hell but their throw isn't very far. If that being the case, how good can it be for tank use, when the average depth is 12 inches and more.

[primavera]

Wow, I'm very impressed by the depth of knowledge here. Just as well, I'll ask some questions that have been baffling me for a while.

Firstly, I've checked the screw in compact fluorescents that I use and it says daylight. Its rated at 5000K (which I suppose the higher the bluer it is?). So is 'daylight' different from plain white light (as in LED)? With daylight incorporating all spectra? I also recall from high school physics and diffraction grating that white light has all components of the visible spectra in it. So why not all white light considered good for plants?

Second, as Wright noted, plants can also use the green range of the spectra (the overlap in the center), although with limited efficacy. So is it possible then to override this "inefficacy" by using more light in the middle spectrum (green/yellow), hence more photons will hit the leaves?

I've also read in earlier websites of planted tank keeping that cheap "cool white" fluorescents are also used with success. Kelvin rating I think is around 4000K. The light seems a bit yellow to me, but the tanks still seem reasonably well grown. Also, books from the 60s and 70s (I think)advocated using incandescents, albeit numerous globes, to light aquariums and terrariums alike (imagine the heat ). Based on pictures in books, it seems to work. So why would such low spectra lights work too?

Going back to ctlam's original post, why are you interested in using LEDs? Is it for some really really small tank? I keep nanos too and I have a 7 and a 9 gallon tank. I just use screw in compact fluorescents and my plants are always bubbling like mad. They are really cheap here, unknown brands around $3. Phillips I think is less than $10. I use 2 bulbs of around the 18 watt range (depending on availability) over one tank ( I know, 36 watts over 7 gallon is a slight overkill, but they are cheap!). They are rated as incredibly energy efficient, light output of 20 watt CF equal to 100 watt normal incandescent, lasting 8000 hours! They give a nice bright normal colour too, and I've used a few over a year now without fail. I've also recently bought 2 18 watt 2 feet Phillips Aquarelle for my newly constructed terrarium, but I'm not a fan of the "girlie pink" colour from the high blue and red spectra. Just bought them for my orchids, read that terrestrial plants are more sensitive to light spectra than aquatics. Anyway, just my(long) 2 cents worth!

Regards

Min

[hwchoy]

normal "daylight" is around 6500K.

you are right that "white" light contains all three primary colours but the key here is the amount of light at a given frequency. this is what the spetrogram shows. if you use a lot of wattage to compensate, you will get other problems such as algae bloom, as those organisms may be able to better use light energy, and then you have to consider other factors such as nutrient balance.

the link below is the spec page of an LED from superbrightLED.com
the bottom graph shows the spectrum of the light emitted from the LED. you can see it peaks at two particular frequencies. you will have to figure whether these peaks are in the useable range for most plants, and how high those peaks are (which is the amount of light emitted at that frequency).

http://www.superbrightleds.com/specs/w5_specs.htm

[Scott_sg]

Hi,
Although this is getting quite technical it should be remembered that the tank water will also influence what light actually goes through, or more accurately, what is in the water. Things like dissolved gases and temperature, organics etc will affect the penetration, so in a lot of ways this is all academic, but still interesting.
The main reason for all of the fuss is that chlorophyll will respond better at different wavelengths. Mostly red and blue, normal lighting tends to have more blue but not so much red. Chlorophyll A is the most important stuff, so generally a bit more red would not hurt. Reddish type plants will tend to benefit more from green light.
Essentially for photosynthesis to work a photon of the right energy has to collide with the chlorophyll and knock off an electron, if the photon is of the wrong wavelength it will just be reflected or absorbed as heat.
Technically it would be possible to set up a tank that looks good, with lots of bright light but starve the plants, if you skipped on the blue and red components.
Pure white light is strictly an even mixture of all of the visible spectrum, but due to what is technically possible this will not happen, most white light tends to have more blue, although there has been a push for daylight lights with more red and green. From an Engineering point of view it is generally easier to make more bluish white light in gas based tubes. Incandescent Lights tend to have more in the way of red. But different manufacturers tend to use day light and white light etc in their own ways so the only way to be sure is to check the actually specifications.
Incidentally in the old days, people would mix incandescent with fluorescent to 'balance' out the colours. But now there is much better technology with the fluorescents, so it is not really done much.
None of this has mentioned intensity, which is simply the amount of photons produced - how 'bright' the light is, not what colour. So Ronnie made a good point about the penetration power.
The colour temperature K is another way of describing the spectrum, in short the colour of a body will change with temperature - red hot, white hot etc in everyday language, eventually if you heat an object enough you will get into the non visible spectrum, UV. ( K is for Kelvins)
Red is about 1800K yellow about 4000KA and so on.
For those wanting to play with UV I have no idea about the LED specifications, but the traditional sterilising tubes work at about 254nm from memory (nm is 10^-9m - the wavelength 0.00000000x), you can see these things in barbers and hair dressers, Kenny might have some for his pliers and other dental 'equipment'. I think they are mercury based tubes.
But if you are planning a DIY UV steriliser, there is one catch. UV will not penetrate glass and most plastics, so the commercial units use a quartz tube to protect the actual tube - which is the expensive bit. The reason they do not run the tube directly with the water is firstly safety and secondly the tubes have to operate at certain temperatures. If I was to try this project I would probably go for a shallow overflow tray or something similar.
Also if you want to use UV sterilisation, then you will need to make sure your conventional filters, Bio, Mechanical are up for it. Since the UV sterilizer will generate organic wastes as it kills things. The marine people can get away with it as they use protein skimmers.
I hope that helps or is of some interest, as an aside I am definitely not even close to an aquatic gardener, but I did take a semester long course in Botany once and it was one of the hardest courses I have taken. So definitely hats off to all of you who can actually grow the stuff. Fish are easy! As to what light is best for your tanks, it is all about informed choice.

Oh and be careful with the LED's it is easy to bugger them with too much current and they also have a polarity, and the white ones are not cheap.

Selemat Hari raya, and thank god for public holidays!

Scott.
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