# 8000k vs 6500k



## ArchimedesTheDog (Apr 9, 2012)

I see a lot of conflicting information on this online, an a lot of it is older. Is the difference between an 8000k fluorescent bulb and a 6500k fluorescent bulb only appearance, or does it make a difference to the plants?


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## jcgd (Feb 18, 2004)

It isn't only appearance, but for our purposes use what you think looks good.

The kelvin rating only describes what the colour of the bulb looks like to humans. The spectral graphs of two 6500k bulbs can be very different, and that's where you'll see the difference to plants. Even then, most bulbs are decent enough that plants can work with it.

The problem with most threads is that eight people beat the knowledgeable ones to it and spread some wrong info. Eight more people once again spread that before someone can straighten things out. The nonsense spreads like wild fire while the good info gets buried.


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## ArchimedesTheDog (Apr 9, 2012)

Thanks. The hood on my 5g doesn't really seem to be distributing light well. I was considering the Aqueon hood for 16-inch tanks. It takes a 14w 15" bulb. It comes with Aqueon's 8000k lamp, which has a spectrum that looks anemic to me, but the plant-oriented lamps I can find at this size are Coralife's Colormax and the ZooMed Flora Sun, both of which get poor marks for aesthetics and fish visibility. I also find one place importing the Sylvania Gro-Lux in that size. Every other plant bulb I can find stops at 18" instead of 15", including the ones branded Aqueon and Coralife. 

Catalina's bulbs stop at 18". Hagen's Sun-Glo and Power -Glo and Aqua-Glo are all available at this size, their other bulbs are not. Eiko makes the size and temperature range, but I can't find spectral info for it. Is there another manufacturer I am missing?

Shoulda got the 10g.


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## wastewater (Apr 5, 2010)

15 inch t8 bulbs are tough to find ~ especially when trying to acquire a particular kelvin rating. Amazon.Com sells ZOO MED ultra-sun (6500k, 15", 14w, t8) bulbs... although a "bit" pricey (about $15 w/o shipping costs).

An interesting read pertaining to spectrum: www.plantedtank.net/forums/lighting/137802-spectrum-analysis-1.html



jcgd said:


> The problem with most threads is that eight people beat the knowledgeable ones to it and spread some wrong info. Eight more people once again spread that before someone can straighten things out. The nonsense spreads like wild fire while the good info gets buried.


I've noticed this with some threads, too.


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## ObiQuiet (Sep 9, 2009)

wastewater said:


> 15 inch t8 bulbs are tough to find ~ especially when trying to acquire a particular kelvin rating.


True. Here are 3, only one of which is 6500k, but much cheaper:
http://1000bulbs.com/search/?q=15in+t8


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