# Question about my lights



## darkfalz (May 7, 2006)

My tank has three lights, 2 x 25 watts and 1 x 20 watts

The 25 watts are 8000 kelvin and look natural colour and are bright. The 20 watts looks purplish and is 15000 kelvin. Are the 8000s for plants and the 15000 for coral or something like that? Or is that purple spectrum good for plants?


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## Guest (Nov 15, 2007)

Yes, usually Kelvin ratings 10000K and above are for reef tanks. They usually use the blueish/purpleish lights on their tanks.

I suggest replacing it with something in the 6500K to 10000K range. 8000K is perfect for plants.


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## Damon (Jan 18, 2005)

10000K is fine for planted tanks but any higher is a waste.


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## darkfalz (May 7, 2006)

Confusingly the small light on my 10 gallon tank claims 18000 kelvin but is only slightly purple, and I have two of different strenghts of tube (20 lux vs 30 lux).


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## Damon (Jan 18, 2005)

Not all bulbs are created equally. Also bulb life has a lot to do with par and color. Older bulbs may not show a color change (some do) but the spectrum does change. 18000K may appear purple to you but may appear bluish to others. K is the color we perceive and everyone's eyes are different. I would still change it to a lower K (6500K-10000K) and change all bulbs every 6 months for peak efficiency.


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