what is 6700k on light bulbs?

  • We are currently upgrading MFK. thanks! -neo

ucng

Feeder Fish
MFK Member
Sep 21, 2009
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San Jose, CA
Hi guys,

Is it just the color? If so what is the difference between the difference numbers? Which numbers are best for a planted tank. Thank you very much
 
ucng;4497603; said:
Hi guys,

quick question, what is the K# mean? Is it just the color? If so what is the difference between the difference numbers? Which numbers are best for a planted tank. Thank you very much

"Many now light like ordinary bulbs. Those with a 2,700 to 3,000 Kelvin (K) number have a warmer, yellower color; 3,500 K to 6,500 K bulbs emit a bluer or whiter light. Energy Star CFLs must include the Kelvin number on the package as of December. Look for CFLs labeled "soft" or "warm" white for light like an incandescent's, and choose "bright white," "natural," or "daylight" for whiter light."
 
5000k to 6700k is ideal for planted tanks, this is the color spectrum that best works photosynthesis in the plant cell. another if you want flowering plants, you need to look into a lower spectrum, something that has a red hue, 2800-3500k... this is especially important if you have plants that are out of the water.

some people say that 10000k also works for the plants, but the only reason that it does is because the spectrum rating is just where its the strongest. a 10000k bulb also puts out light on lower levels that is also in the 5000-6700k but it is overpowered by the white 10000k color.
 
anything from 6500k to 10,000k will grow any freshwater plant just fine. hell, even the Powerglo 18,000k will grow plants well, although based on the kelvin scale it's not truly 18,000k. who knows what it is...it's has a purplish color to it
 
So if you have something like a dual bulb fixture where you can run two different k lights, what would the ideal setup be? Two 6700k? Does actinic do nothing for FW planted tanks?
 
The question is open to personal interpretation. Obviously the most efficient is both bulbs in the exact range, however A) its subjective based on strong duty cycles from ballists, which essentially points to quality of design & B) we still have to view it, so colour range becomes a personal factor.

And Zip, even for marine. Its all aesthetics in that range.
 
jcardona1;4498505; said:
anything from 6500k to 10,000k will grow any freshwater plant just fine. hell, even the Powerglo 18,000k will grow plants well, although based on the kelvin scale it's not truly 18,000k. who knows what it is...it's has a purplish color to it

Purple? Badass...now I want to get new lights...again. :D
 
After much research I decided on one 6700K bulb and one 10,000K bulb on my planted tanks. Those are the tanks with two T5HO bulbs. On another tank that has four PC bulbs I have two 6,700K and two 10,000K bulbs. The 6,700 has a more yellow color and the 10,000 is more white. This combo has worked well for me and my plants grow really well.

Actinic bulbs do nothing for live plants.
 
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