# help please lighting a 2 ft cube



## kirk (2 Jan 2013)

Hi all, i am looking into the led lighting and making up my own lighting asembly. currently i am running a twin 8w t5 unit with a ebay clip on 96 led strip.		i was up until last week running 4 8w t5 and plants looked almost at a standstill.	 so the plans are to use 2 x10 w 20000k cool white led chips with 1x10w blue. 3x heat sink 2 x computer fans.	 i do not want to suspend lighting as i like the tank coverd not to loose leaping fish or shrimp.so will make a hood from stainless.   Am i going  down the wrong route chasing kelvins/light temperature. ?  i have had some good growth since putting the led strip back on and viewing light is better.  oh and the chips/driver are all ebay items.   any comments experences welcomed and thanks in advance.​


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## Danny (2 Jan 2013)

You are way off with your light spectrum/kelvin for growth, what you have listed above is the most common marine combo for aesthetics. You need to be using 6500k for optimum growth and forget the blue.

Just because a light is bright and looks white does not mean it is good for what you are using it for, a lot of corals and all plants are photosynthetic and rely on the sun for there "food" the sun's spectrum is 6500k. Most people with marine frag tanks use 6500k tubes for optimum growth but will use the 10k+ and blue on the DT becuase it looks better.

If growth is what you are really after stick to 6500k


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## jack-rythm (2 Jan 2013)

Really hate to say this Danny but Kelvins have nothing to do with plant growth mate. These are solely to measure brightness of bulbs. Forget how much kelvins a light unit has. Its unfortunate that this information gets into the wrong hands. You can grow plants under anything. Colour is also a 'moo' point  You can grow plants under a cruddy desk lamp if you needed to


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## Danny (2 Jan 2013)

Oh dear, you still hung over from new year mate lol So you recken a blue 420nm ( actinic ) will grow plants just as well as a 6500k?


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## wazuck (2 Jan 2013)

Ok 20k and blue is more suited to a marine setup and you may not get the look you want with that. 6500k is what the light would look like at midday. The problem is with LEDs the spectrum isn't that great at making the colours "pop" and you will end up with a washed out look. I'd say your better off going with a mix of warm, neutral and cool white to get close to that daylight look but still have the colour pop. Even better would be to have each type of led on a separate string with dimmable drivers so you can mix them easily and get the colour you want. You could add green, red and blue LEDs which say cool whites and mix them for the same effect but I feel the first method will be easier. Try to group the LEDs do they mix well and you dont get different coloured beams in your tank. Hope this helps.


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## wazuck (3 Jan 2013)

Danny said:


> Oh dear, you still hung over from new year mate lol So you recken a blue 420nm ( actinic ) will grow plants just as well as a 6500k?



The kelvin rating applies to the light we see. If 6500k is the best for growing plants then why do ADA (correct me if I'm wrong) 7000k or 8000k. Wouldn't they use 6500k? Plant growing LEDs on eBay use blue/red and blue/green/red combos. They grow plants but certainly aren't 6500k. perhaps someone should gather some par data on 420nm compared to 6500k to see if there is a big difference.


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## jack-rythm (3 Jan 2013)

Danny said:


> Oh dear, you still hung over from new year mate lol So you recken a blue 420nm ( actinic ) will grow plants just as well as a 6500k?


 
No mate im not, although it was a heavy one. 

you can essentially grow plants using green, red, blue, what ever you want. The output looks nothing like daylight but they grow plants due to the spectrum they have. So kelvin isnt as important as such, it may well give you a better par depending on the rating but it is basically just the light we see. Worry more about par than anything. Avoid the kelvin myth.

Cheers Danny


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## wazuck (3 Jan 2013)

Kelvin is the colour temperature. Nm is nanometers. A blue actinic is something like 71,000kelvin. Par is Photosynthetically active radiation. Aslong as the par is good it doesn't matter what colour the light is.


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## kirk (3 Jan 2013)

Looks like im back to the drawing board then.my main problem is i need to punch enough light down throught 20" of water to grow carpeting plants. i have also been told that plant need certain amount of watts per ltr ? so i will now look into par and different colours at 6500 k and return with more questions. thankyou for your replies/ input  is there an easyway to post pics uo rather than a linkk?


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## jack-rythm (3 Jan 2013)

TBH buddy I would forget kelvins altogether unless this is the particular brightness your going for.. just find out your par readings. I personally am not up to date with par readings and suitable light sources for high tech tanks, I just know the basic whats important and whats not. Im more of a low tech man, and with low tech lighting it is the least important for me. But however there are some LED gurus out there that will get on this for you. Wazuk knows his 'LED world of knowledge' extremely well and so do a few others, so I wish you luck buddy, someone will help you.

Jack


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## Antipofish (3 Jan 2013)

Hi

LED's are most likely to have the intensity you need for carpeting plants but plenty of guys on here have had success with T5's (with reflectors) growing carpets.  Is 6500K your favoured colour rendition ?  If so fine, if not, choose whatever you like.  This link may help...  James' Planted Tank - T5 Lighting On The Cheap


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## wazuck (3 Jan 2013)

kap k said:


> Looks like im back to the drawing board then.my main problem is i need to punch enough light down throught 20" of water to grow carpeting plants. i have also been told that plant need certain amount of watts per ltr ? so i will now look into par and different colours at 6500 k and return with more questions. thankyou for your replies/ input  is there an easyway to post pics uo rather than a linkk?


 
Adding optics will help punch the light down there if you think you need it. But they may not give a good light spread unless raised above the tank.


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## Danny (3 Jan 2013)

Plants will grow under 2000k - 10,000k but 6500k is the best as it is the closest to natural sunlight. People can live on just beans and water but it does not mean they do best on them.


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## wazuck (3 Jan 2013)

Danny said:


> Plants will grow under 2000k - 10,000k but 6500k is the best as it is the closest to natural sunlight. People can live on just beans and water but it does not mean they do best on them.



Any solid evidence to back this claim?


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## kirk (3 Jan 2013)

living on beans and water wont produce "solid" evidence.


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## jack-rythm (3 Jan 2013)

kap k said:


> living on beans and water wont produce "solid" evidence.


 
 I know you can live on Guinness too! lol


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## ceg4048 (3 Jan 2013)

Danny said:


> Oh dear, you still hung over from new year mate lol So you recken a blue 420nm ( actinic ) will grow plants just as well as a 6500k?


Yes, I have done it, many times. It requires no special trick or additional burden. Just insert bulb and flip switch. You have been duped by people who know less than you do.



Danny said:


> Just because a light is bright and looks white does not mean it is good for what you are using it for


Actually, that's exactly what it means. Review the thread Cheap ASDA Ikea etc light bulbs | UK Aquatic Plant Society as well as the links they contain. Then you will understand more about light than 99.9% of the planted tank world's population.

Cheers,


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## rolexbene (3 Jan 2013)

How "bright" a light appears has more to do with how much light is output in a given area visible to the human eye, with "brightness" being at a maximum in the green/yellow spectrum (middle of visible spectrum, or around 600nm). If you want to optimise plant leaf development (blue light) and stem elongation and colour (red light) you need light in both the blue and red spectra for photosynthesis. You need a mix of blue and red for your plants, and green for you (brightness as perceived by humans). Kelvin for light, is a measurement of the heat given off by a black body, which relates to the spectrum of light given off. Nanometers are a measurement of one specific wavelength of light (one specific colour). Kelvin is a rating of all the colours existing in a light source, but it does give an indication of the nm peak within the spectrum. It is true that 'full spectrum' bulbs are referred to as bulbs between 5000 Kelvin (K) and 6500 K and are considered to be best for planted tanks, however, to get a concussive indication of whether a bulb is good or not, you need to be looking at the nm in relation to photosynthesis, for this you would no doubt need to find a data sheet for the bulb in question or have testing equipment. On another note you will find many cheap bulbs can work wonders for growing, I have had great results with cheap cfl bulbs, best bets in moh is to just aim for a full spectrum bulb around the 6500-1000k and you should be all good.


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## Antipofish (3 Jan 2013)

Danny said:


> Plants will grow under 2000k - 10,000k but 6500k is the best as it is the closest to natural sunlight. People can live on just beans and water but it does not mean they do best on them.


 
I suggest you avail yourself of the many discussions (most of which include technical references) on this subject.  What you have written above is complete nonsense.  Plants will grow just as well under practically any light temperature.


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## kirk (3 Jan 2013)

well im now more confused than before starting the thread. so i treated myself to a new bulb and plants  . every trip to an aquatics shop makes me buy plants. the bulb is aqua glo hagen 18,000k they recomend a using with power glo or life glo .they do a flora glo 2800k and a sun glo 4200k  .i have ignored kelvins although it may not look like it by the bulb i have just got. any experences with the flora gro anyone?​


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## Antipofish (3 Jan 2013)

Flora grows are fine, but Im not sure why anyone would want an 18000K bulb for a planted aquarium... its very blue and IMO will make a lot of the colours washed out.  Mixed with something else it could look ok though I guess.  And the best rule to remember is "If it works for YOU, it WORKS"


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## kirk (3 Jan 2013)

its looks better than.my 10000k. the box the tube came in says. ehances fish colours and for planted aquariums.its bringing out more reds pinks the malvern stone looks brighter the plants look different shades of green. so i supose its a case of watch wait and see. i will dig the thread up again in a mth or so and let you all know if thinh have got better or ive just thrown more money down the drain. thanks all. forgot to say im still running the led strip which may be stopping the washedout look.​


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## Antipofish (3 Jan 2013)

Im sure the LED strip will be adjusting the rendition.  But like I said, if it works for you, it works


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## rolexbene (3 Jan 2013)

Photosynthesis (Plant growth) is very directly related to nm (nanometers) of light. The overall colour (Kelvins) is somewhat related to specific nm peaks.





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).

So at 4,500K, the peak wavelength is 666nm (red) at 6,000K the peak wavelength is 500nm (bluish green) and at 7,500K the peak wavelength is 400nm (deep blue)

Following Wien's law is however, not the greatest guide as you cannot see the full nm spectrum, obviously you cannot just grow plants under any lights, try a hydroponics setup with 1000w of incandescent bulbs and see what happens(Not a lot). To find out if a bulb is good for growing plants under, just follow the very simple rules of specific nm wavelengths of light and look at a data sheet for the bulb in question. Such as:
http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/XLampXML.pdf


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## Ian Holdich (3 Jan 2013)

plants will use any types of light, kelvins really don't matter...they really don't. Par is more important, not the kelvin.


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## Antipofish (3 Jan 2013)

Ian Holdich said:


> plants will use any types of light, kelvins really don't matter...they really don't. Par is more important, not the kelvin.


 
LOL its like hitting your head against a brick wall trying to get people to believe and understand this isnt't it Ian.  They read some physics and think its absolute.


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## Danny (3 Jan 2013)

If you guys read what I said properly you would of seen I said 6500k IS BEST for growing plants, not that it is the only light they will grow under. 6500k has been proven over years to have the best results as it is the closest thing to the full spectrum of natural sunlight for both plants and coral.

Someone better tell all the farmers they are wrong relying on the sun to grow there crops at there best then..........


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## ceg4048 (3 Jan 2013)

rolexbene said:


> Photosynthesis (Plant growth) is very directly related to nm (nanometers) of light. The overall colour (Kelvins) is somewhat related to specific nm peaks.
> 
> 
> There IS a relationship between a colour temperature and the peak wavelength in its spectrum . It's called Wien's law.
> ...


I guarantee you that I can, not only grow plants under any light, but I can grow them so that they are in superior health.The peak wavelengths are meaningless. Peak wavelengths do not achieve anything. It is the total area under the curve that determines the energy levels input to the plant. Having a sharp peak at a given frequency is meaningless if that frequency is not available. Have you ever thought about that? There are plenty of places in rain forests where those peak frequencies are not being shone on the plant, especially if the plant is buried under brown tea stained water. It would not be very efficient to be dependent on a few peak wavelengths.

The graph you show above illustrates the response of only three types of pigment proteins. For these particular proteins, Chlorophyll-A, Chlorophyll-B and Carotenoids. The plant has available to them hundreds of other pigment proteins along the entire visible spectrum, especially in the region of 550 to 650nm. These pigments not only absorb those frequency, but they have the ability to fluoresce and to actually CHANGE the color of the incident light to a color that another pigment can absorb.

The reds and blues of the Kelvin lovers are important to plants in much different way than the tunnel vision of the propagandists. The appearance of different colors changes the behavior of the plant. Certain proteins are produced under certain colors. The method of food production changes under some colors. Metabolic processes change as a function of color. None of these are related to plant health because the plant can manipulate the light to trick it's own receptors. That is the genius of plant design. That is why plants are so amazing. They are not amazing because they have some kind of drug addiction to 6500K.


Cheers,


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