Difference bewteen 6500k and 6700k?

[RussGB]

I just got my new T5 set up. The manufacturer sent 6500k tubes and I really wnated 6700k. Its too much grief to send them back, but do I really need to?

What is the difference between 6500K and 6700k (and don't tell me its 200k!)? Will my plants really care? I know its a bit cooler which pushes it more to the red end of the sepctrum....

[CichlidFan]

Re: Difference bewteen 6500k and 6700k?

Can I say "not much" ?

Actually, I believe the K stands for Kilowatt, and it would also be my belief that the 200 watt difference in wattage, would not have a big impact on plants or fish.  I could be wrong though...??


CF

[Mzungu]

Re: Difference bewteen 6500k and 6700k?

It actually really means nothing at all to the plants. It's only for human purposes that they give bulbs K-ratings, it basically tells you what the overall color will look like to you. It says nothing about the spectral quality of the lamp. There very well could be more "red" in the 6700K than the 6500K, it's really just an average. You have tons of possibilities of spectral distributions for each K rating.

67K and 65k will probably not have a very noticeable difference at all. Technically, the 67K would look a bit more blue/white and the 65K more yellowish. But they're pretty close together.

And the plants really only care about the spectrum, anyways. If they're full spectrum bulbs, you're probably safe.  :)

[nacra99]

Re: Difference bewteen 6500k and 6700k?

For all intensive purposes, 6700K and 6500K are pretty much the same thing.

Technically, 67K will be slightly bluer than the 65K but between the 2, it won't have a very big impact on plants or visual effect.

[RussGB]

Re: Difference bewteen 6500k and 6700k?

Can I say "not much" ?

Actually, I believe the K stands for Kilowatt, and it would also be my belief that the 200 watt difference in wattage, would not have a big impact on plants or fish.  I could be wrong though...??


CF

LOL - "not much" - thanks CF! :wink:
Actually I think the K is for Kelvin, i.e. degress Kelvin (measured in the same scale as centigrade, but with zero at absolute zero, -373 degrees C). Its supposed to give an idea as to the spectrum of the bulb, i.e. the output is the same spectrum as something glowing at 6700K.

My physics is good, its my biology/botany that sucks! I am not sure how good these bulbs are -  they came with the units I bought. I guess I have to try it and see....

[CichlidFan]

Re: Difference bewteen 6500k and 6700k?

I learn something every day on this site....

6700 Kilowatts does sound like alot of wattage, now that I think about it ... :)

CF

[eklikewhoa]

Re: Difference bewteen 6500k and 6700k?

I have both but in PC's.....there is a slight difference to the eye but since they are T5's the appearance might be intensified but as for the plants it won't make much difference.

[RussGB]

Re: Difference bewteen 6500k and 6700k?

So you guys think i am good to go?

Thanks all for your input and interest....

[eklikewhoa]

Re: Difference bewteen 6500k and 6700k?

Yes.

[Leprae]

Re: Difference bewteen 6500k and 6700k?

Actually I think the K is for Kelvin, i.e. degress Kelvin (measured in the same scale as centigrade, but with zero at absolute zero, -373 degrees C). Its supposed to give an idea as to the spectrum of the bulb, i.e. the output is the same spectrum as something glowing at 6700K.

You beat me to the correction.   :?   Though, to correct you, it's -273 degrees C not 373.  Also, it's important to note that the bulb doesn't get that hot, since that's excessively hot.  It is, as you pointed out, an indication of light spectrum, though I'm not entirely sure how the correlation to Kelvin units came into play (except that cooler things burn more orange reds and hotter things burn more blue).  Along those lines, lower Kelvin light sources produce more reddish light, and higher Kelvin light sources produce more blue/violet lighting (great for marine tanks).  The visible and physiologic difference between 6500K and 6700K shouldn't be noticeable.

[nacra99]

Re: Difference bewteen 6500k and 6700k?

The kelvin rating for lighting is derived from the color of a piece of carbon at a particular temperature.
I.e what is the color does a carbon block emmit when you heat it to a particular temperature.

For example when you heat a carbon block to 2500K, it will produce a glow like the evening sun, when you heat it to 10,000K it will produce more of a bluish glow.

[wolfbane]

Re: Difference bewteen 6500k and 6700k?

Wow! Finally an explanation of the Kelvin rating system! I had wondered what that meant, and its been way too long since Chemistry and Physics classes for me to remember much.

[Mzungu]

Re: Difference bewteen 6500k and 6700k?

Yeah, the only problem is I think a lot of companies out there that make aquarium bulbs, etc. sort of make up their own K ratings...oh well!

I usually try to buy bulbs that actually publish a reasonable spectral distribution for each of their lamps, since for each K rating the graph can be totally different.