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Joined
May 18, 2005
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1,250
Location
Milwaukee
I'm getting new lights for my grow chamber since my project is done, I have more space, and my others lights broke. So shopping bulbs around I found these two types. Which one would be the better bulb to get?


T8 32 watts
Lumins 2800
CRI 85 6500K

T12 40 watts
Lumins 3050
CRI 75 6500k
 
Joined
Oct 12, 2001
Messages
4,641
Location
Far Away NY
If your fixture will run the T12 I would use them as they put out a little more light. You're talking 250 lumens for each bulb, which is not exactly insignificant when you have multiple bulbs.
If you are worried about the difference in CRI don't be.
 
Joined
May 18, 2005
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1,250
Location
Milwaukee
I plan on running about 6 so yeah 1500 lumens is a lot. I was just wondering if T8 is better or you pick more watts. Thanks a lot.
 
Joined
Dec 10, 2007
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Location
Harrisburg, Pennsylvania
CRI affects how true and natural your plants' colors will look under the lights. CRI 75 is fine and your plants will look good under them. Plants don't care about CRI.
 

vraev

Carnivorous plant enthusiast
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Hmm....I personally don't have too much experience..... :( but I have tried getting a 2x 2' T12 at 5000k and compared to a 2' T8 3200K + 5000K, it was definitely weaker.
 
Joined
Oct 12, 2001
Messages
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Far Away NY
It really depends more on the bulb. Bulb manufacturers make many different formulations of phosphors to give certain color temperature and CRI. Lumen output can vary nearly 30% from one bulb to another in the same diameter and length. So unless you compared the same exact bulb in T8 vs T12 it's like comparing apples and oranges.

Most likely the one appeared brighter to you because of the 3200k bulb which is more red. Bluer wavelengths appear dimmer to us (think of the growlux plant bulbs which are bluish purple from mainly blue wavelengths and some red tossed iin). Plants however don't care how bright the light looks to our eyes.
 
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