# LED Lighting with Plants Question



## Fishnshrimp2 (Sep 13, 2013)

If I wanted an LED light capable of growing plants do I need to look at the K value or is the wattage more important?

Also I have a 20g tall tank, should I just go with T5HOs or if I get the right LED will it still work?


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## Izzy- (Jun 11, 2014)

I have a Current USA fresh water LED plus on my 20 high. All my plants are doing great.

As many of the members here will tell you , Watts don't tell you how bright something is.
Look at the PAR rating. 

A current USA freshwater LED plus on a 20 high gives you a par rating of 30-35 depending on the substrate . Which means you can grow some medium light plants.

I would recommend this LED fixture, plus it has cool lighting settings.

Plant stock : Wisteria, java fern, Anubias, jungle val, tiger lotus, Aponegeton Ulvaceus, Dwarf sag, normal sag, and giant sag. All doing good with this fixture.

Sorry for non scientific names on some. If you really wanna know I can get back to you.

Bump: Oh and look at the kelvin rating .Don't look at watts. That just tells you the energy consumption. anywhere from 5500k-7500k would be okay , but 6500k would be best.
Shoot for 6500k


Current USA freshwater LED Plus is 6500k.


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## Fishnshrimp2 (Sep 13, 2013)

Thanks for clearing that up for me. I didn't know if the K rating on LEDs was important like it is on flourescent lighting. I'll look up the Satellite+. It looks low profile which is one of the reasons why I was considering LED lighting, plus I hear you don't have to replace bulbs.


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## klibs (May 1, 2014)

K rating is never important. It is just how our eyes interpret the light. The spectrum that the light outputs / at what intensity (PAR) is what is important.

6500K is commonly recommended because at that color temperature the light usually outputs the correct spectrum needed for plant consumption. (spikes in the red / blue spectrum that chlorophyll can absorb). Higher / lower temperatures usually have a heavy amount of either blue/red so they are not really as good for plants. The K rating is again just how our eyes perceive the color.

Many people have great success with low-tech Current Sat + setups. I've never owned one but it is a great low-med light fixture from what others say.


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## jeffkrol (Jun 5, 2013)

klibs said:


> 6500K is commonly recommended because at that color temperature the light usually outputs the correct spectrum needed for plant consumption.


I'm pretty sure that "error" occurred on the basis of that is what "daylight" averaged..
W/ CCT lights (LED and flour.) that is meaningless..










Actually 6500k CCT is probably one of "the worst" color temp. for plants..
CCT @ 6500k is nowhere near as balanced as a Daylight K of 6500, generally speaking..

but one of the better looking.. 

it is/was no more than a compromise..









coral centric but do you see the "problem" here?









a combination of say 6500k's and 3500k's are much more "ideal" for plants..more like 5000k CCT on average..


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## klibs (May 1, 2014)

jeffkrol said:


> I'm pretty sure that "error" occurred on the basis of that is what "daylight" averaged..
> W/ CCT lights (LED and flour.) that is meaningless..
> 
> 
> ...


yeah it totally depends on the bulb manuf. too. I think they can vary pretty widely.

All I know is that my BML Dutch grows plants 10x better than my 6500 / daylight 'AquaFlora' T5 tubes. Lights specifically geared towards plant growth are the best way to go IMO.


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## jeffkrol (Jun 5, 2013)

klibs said:


> yeah it totally depends on the bulb manuf. too. I think they can vary pretty widely.
> 
> All I know is that my BML Dutch grows plants 10x better than my 6500 / daylight 'AquaFlora' T5 tubes. Lights specifically geared towards plant growth are the best way to go IMO.


Yes and different 6500k's can be completely different in spectrum.. 
My minor point, and to take the cloths of the Emperor is 6500k is marketing..
w/ out know the "components" in the 6500k spectrum.. 

fortunately for LED's the rich blue component makes them fairly ideal on a PAR/visual spectrum.. 
They just lack the red.......


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## Bruce6000 (Jun 18, 2009)

So generally speaking, if you don't have the money for a nice LED fixture geared for plant growth and your next option is a CFL, is it safe to say that 5500K is a better option than 6500K?

Because as luck would have it, I have several 5500K CFLs hanging around, not really being used becuase everyone is always pushing 6500K, so that's what I use on my tank. There's so much contradictory information all over the place, with the exception of marijuana growers who sware by 6500K and 2700K CFLs.


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## Xiaozhuang (Feb 15, 2012)

+1 on all the people that say K doesn't matter in this context.

5500k better than 6500k ? that statement is also meaningless without knowing the PAR or spectrum graph, unless you mean it looks better. BTW if you're using bulbs from the bigger manufacturer's, you can check their websites for spectrum charts if you're really that particular.

I've used everything from 2200k to 6500k (CFLs), and settled on the 2200k cos I have spares, and don't mind the warm looks. Use what you have, it doesn't make all that much of a difference in growth, compared to other factors (substrate, water etc), choose the one that visually looks good to you.

Some low tech examples using said cfl in this thread:
http://www.plantedtank.net/forums/showthread.php?t=736393


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## Bruce6000 (Jun 18, 2009)

I've looked for PAR chart date for General Electric CFLs and came up empty handed.

Okay, so let me ask a simple question. Light absorption for plants is most efficient at 400nm and 700nm, red and blue spectrums, how do you select a CFL based on that info?


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## jeffkrol (Jun 5, 2013)

Bruce6000 said:


> I've looked for PAR chart date for General Electric CFLs and came up empty handed.
> 
> Okay, so let me ask a simple question. Light absorption for plants is most efficient at 400nm and 700nm, red and blue spectrums, how do you select a CFL based on that info?


you won't find PAR charts but you can infer from spectrum and intensity..









PAR will depend more on reflector efficiency..


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## Bruce6000 (Jun 18, 2009)

Thanks for the chart! What you said about PAR makes sense. A good quliaty reflector can intensify light and in turn increase PAR. 

I'm still trying to understand the whole color temperature deal and how that impacts plant growth. For example, I know that a lot of folks in hydroponics use 6500K bulbs for vegetative growth and when they want to trigger flowering, they switch to 2700K bulbs. That tells me that color temp is not just marketing hype. The plants respond to different temperatures- (but I know it's not temperatures, but rather light spectrum)- and I'm wondering if aquatic plants would respond similarly. 

I'd be interested in seeing a chart like the one you just shared but for 5500K CFLs


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## jeffkrol (Jun 5, 2013)

Bruce6000 said:


> Thanks for the chart! What you said about PAR makes sense. A good quliaty reflector can intensify light and in turn increase PAR.
> 
> I'm still trying to understand the whole color temperature deal and how that impacts plant growth. For example, I know that a lot of folks in hydroponics use 6500K bulbs for vegetative growth and when they want to trigger flowering, they switch to 2700K bulbs. That tells me that color temp is not just marketing hype. The plants respond to different temperatures- (but I know it's not temperatures, but rather light spectrum)- and I'm wondering if aquatic plants would respond similarly.
> 
> I'd be interested in seeing a chart like the one you just shared but for 5500K CFLs


Each light unfortunately can have a different spectrum but still "add" to 5500K or whatever.. Just a typical 5500K









A more interesting chart:









for fun.. some 96CRI 5500k lights:
http://www.naturallighting.com/cart/store.php


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## Bruce6000 (Jun 18, 2009)

Hmmm, makes sense, I think...:hihi: Well, it's only a matter of time before I drop CFLs and go with LEDs geared towards plant growth. Thanks again for sharing. BTW- awesome link


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