# Does Daylight (6500K) = Full Spectrum?



## Choco (Dec 8, 2007)

Hi...just wondering if a light bulb is described as Natural Daylight with 6500k rating, does that equivalents to the light being full spectrum? If not, are they "usually" full spectrum?

How important is it for the light to be full spectrum to grow plant? What happens if you use lighting that is not full spectrum but is a daylight 6500/5000K


Last question..is this a full spectrum light? http://genet.gelighting.com/LightPr...lectionFilter=FT0010:General Purpose_Standard


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## unirdna (Jan 22, 2004)

The heat of the bulb/filament determines the spectrum. "Full spectrum" is seller's talk. Truth is that the spectrum varies in different parts of the earth. The surface of the sun is around 5000K. So, most "full spectrum bulbs" should burn at that temp. But that does not speak for the bulbs intensity - that is measured in Lux, or, more crudely, watts.

To the point: The bulb (link) you provided has been tested in many aquaria (including my own), and grows plants well. One over a 10 gal for low light, 2 bulbs for high light. 2 Bulbs is standard for a 15g or 20g. They are not as efficient as strip lighting because of their coiled design, but they are great if you are on a budget.


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## Birdman (Feb 19, 2008)

unirdna said:


> The heat of the bulb/filament determines the spectrum. "Full spectrum" is seller's talk. Truth is that the spectrum varies in different parts of the earth. The surface of the sun is around 5000K. So, most "full spectrum bulbs" should burn at that temp. But that does not speak for the bulbs intensity - that is measured in Lux, or, more crudely, watts.
> 
> To the point: The bulb (link) you provided has been tested in many aquaria (including my own), and grows plants well. One over a 10 gal for low light, 2 bulbs for high light. 2 Bulbs is standard for a 15g or 20g. They are not as efficient as strip lighting because of their coiled design, but they are great if you are on a budget.


How many of these would you recomend over a 5 foot long. 2 foot deep tank?


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## lauraleellbp (Feb 3, 2008)

Bird- Kelvin spectrum ratings only refer to the color of light that the bulbs put out. Plants generally can use light in the 5000-10000k range.

The question you need to ask is how many watts you need- and that doesn't have anything to do with a bulb's color.

If I remember correctly, your plan is to light a 125gal tank, and you want to stay with a low-light plant setup, is that correct?

If that is the case, since low light is considered 2wpg or less, you will want the total watts on your light fixture to put out approximately 250watts.

I know you love DIY setups- I would encourage you to check out the retrofit kits on www.AHSupply.com. IMO 2 of their 96watt strip lights would be awesome over your tank.


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## Birdman (Feb 19, 2008)

lauraleellbp said:


> Bird- Kelvin spectrum ratings only refer to the color of light that the bulbs put out. Plants generally can use light in the 5000-10000k range.
> 
> The question you need to ask is how many watts you need- and that doesn't have anything to do with a bulb's color.
> 
> ...


Thanks for the tip. Looks nice and not out of range price wise either.


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## unirdna (Jan 22, 2004)

Good advice, lauralee. That is a big tank to light. A ton of compact spirals would prove more trouble (and cost) than it's worth. That is why I didn't recommend any scenarios greater than a 20g . Have fun with the DIY project. A&H make quality stuff.


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## crazy loaches (Sep 29, 2006)

unirdna said:


> The heat of the bulb/filament determines the spectrum. "Full spectrum" is seller's talk...


Just wanted to point out this is only really true for incandescent type lighting. For fluorescent the heat of the bulb/filament has nothing to do with the spectrum. Pretty much any fluorescent bulb actually discharging mostly UV light, and it is the type of phosphors in the coating that will convert the UV into other visible wavelengths. I dont know if 'full spectrum' is an official term, I usually take it to mean there are at least red green and blue phosphors or more. And no, plants dont require full spectrum, many plant bulbs put out mostly just reds and blues. But full spectrum usually implies that the plants are at least getting what they need and then some, so some consider them the 'safe bet'.


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