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Is 6500K absolutely necessary for plant growth? My fish are so washed out with 6500K

19K views 14 replies 8 participants last post by  inkslinger 
#1 ·
Was wondering if I can do one of those Gro Lux bulbs by Slyvania that is rated around 3000K along with a 6500K bulb. I tried using two 6500K T8 (18" 15 watts each) and my tropical fish look sort of grayish in color and not as attractive.

Seems so many people here are suggesting the use of anything over 5000 for plants. But I do not see anyone talking about how this makes the fish look. Can anyone comment?

I thought of mixing one Gro Lux bulb with a Daylight GE 6500K bulb. Can anyone knowledgeable help a newbie please? Just want to know if I sacrifice healthy plants by using the Gro Lux bulb with a 6500K Daylight bulb by GE.

Thanks,
Adrien
 
#3 ·
But don't the 8000 and 10000 bulbs create an even starker type white light and therefore wash out the fish more? The Gro Lux is around 3000K, I know that is low but they do make the fish look more attractive. I thought the higher the number, the whiter the light and the grayer the fish will look.
 
#6 ·
Thanks for the response, guys. When I read the description on the Gro-Lux bulbs it says that it has more focus on the blue and red color wavelength which is supposed to support bushier compact plant growth.

So that is why I am a bit confused if the Kelvin rating is on the lower side yet is supposed to have more blue and red like the packaging of my Gro Lux bulbs states.
 
#11 ·
The color temperature of a bulb gives you a rough idea of what the light will look like over the tank. As color temp increases from 5k to 10k the perceived color of the light goes from a reddish-yellow to blueish-white.

The color spectrum of bulbs is different than the color temperature. That is why it can be helpful when purchasing bulbs if the bulb manufacturer makes a graph or chart of the color spectrum available.

Bulbs of the same color temperature from different manufacturers can have very different spectral output. If you visually compare say two 10k bulbs they may both appear to have bright blueish-white light but the peaks in the red and blue parts of the specturm may be very different. The difference is not something you will see with your eyes but it is something that effects the way the plants grow.
 
#12 ·
I am old-school and tend to like bulbs with color temperature in the range of 5000-6500K. The bulbs in this range are called "daylight" because this the color temperature of natural sunlight.

A lot people prefer light with higher color temperature like 10,000K or even 20,000K, feeling it is more "crisper". I think it comes down more to personal preference and the plant should grow well enough as long as there is enough light.
 
#13 ·
The Daylight GE 6500K bulb will probably work well for you. I used to use it in the T5HO version and it was rated on a reef site as having one of the better PAR ratings.

http://forums.saltwaterfish.com/forum/thread/348223/lots-of-t5ho-info-par-and-lamp-pics#post_3003505

The GE looks a little too yellow for my eyes so, you might want to pair it with a 10K bulb. It doesn't look quite as yellow as the Geismann midday 6K bulb but still not as white as the 10K bulbs. I have Geismanns too. They are awesome plant growers but not great to me visually. IMHO, it's not necessary to spend $30.00 for a light bulb. The Current and GE bulbs work quite well. They can still cause you to trim weekly.
 
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