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Discussion Starter #1
I was in my local pet store today and I saw an UltraGlo 48", 40W Bulb that claimed it was 18,000K- My jaw dropped!. I asked the guy about it and he said it was that in its certain spectrum... any ideas? Anyone ever heard of this bulb before? It was like $24.
 

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Those are metal halides, which are in a totally different category. I have 14 bulbs and I'm not paying $336 for vivarium overkill :!:
 

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Discussion Starter #6
So when I look for bulbs... what do I look for? Sites say broms need 6500 K or higher to thrive. What does everyone look for. I see Lumens listed all the time, but i don't really know what lumens range to look for.
 

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It has been said that the color temp really doesn't have much effect on (vivarium) plant growth...plants will use just about any color for growth but green.
The color temps suggested by others are primarily for keeping the viv looking real...though I have seen somewhere the suggestion for using a 6500 or higher for broms...if anyone has any evidence to back that up, it would be nice to see.
CRI is how acurate the bulb reproduces this color temperature, on a scale of 1-100...the higher the better.
Lumens are just a measure of light output...this is (fairly) simple...you want as much as you can get (usually).
There is also a much more advanced measure of light for growing plants...it is a measure of PAR (photosyntheticly active radiation)...though you won't see those numbers very often...even if you look real hard. (wish it weren't so)
 

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Dancing frogs said:
...though I have seen somewhere the suggestion for using a 6500 or higher for broms...if anyone has any evidence to back that up, it would be nice to see.
I think it is hogwash. You already said it. Photosynthesis occurs when a photon of light from just about anywhere in the visible light range except green hits a chloroplast. The intensity of the light determines the number of photons per second that will hit the plant. The color temp is just not that important.
 

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I have read that some plants do better with stronger parts of the spectrum though. Depending on the plant. For example some need more red or blue.

Most broms will grow under any light, but some may lose there reds and other bright colors in lower light.

I use Philips Daylight bulbs over my tanks and have had good luck. You can get a 4ft shop light and the bulbs for about $20 at Home Depot. These are the T8's which use less power and put out more light so best of both worlds. I think these bulbs are 2800 lumens at 6500k.

Hope that helps, the lighting thing can be a pain as everytime you add more you add heat. The compact flourecents put off mroe light, but the heat in many cases is tough to manage. Oh ya, and they cost a ton more.
 

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mydumname said:
Ouch, my eyes! My 6500k's are bright, these 1800k would probably light up my street through the window.
The color temp has nothing to do with how bright it is. You can have a very bright 4000k bulb an extremely dim 20,000k bulb. You actually lose PAR as color temp goes up.
 

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kyle1745 said:
I have read that some plants do better with stronger parts of the spectrum though. Depending on the plant. For example some need more red or blue.
There are some very subtle differences in the way some plants react to the different portions of the visible, UV, and near infrared spectrum. Most of these, to my knowledge, have to do with how stem elongation or flowering occurs. But these are more of interest for commercial growers than people who just want pretty, healthy plants in their vivs. There is and exception though. Aquatic plants. Shorter wavelength light has more energy in it so UV to green has more energy than yellow to infrared. Water filters out light and the portion of the spectrum with the least energy gets filtered out first. So the blue and ultraviolet light is what penetrates deepest underwater so the chlorophyll of many aquatic plants is optimized to take advantage of that color of light. That's why reef tanks use actinic bulbs.
 

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FCA said:
Yes, the Kelvin rating is just the color of the bulb. You have to take into account the CRI, PAR, and/or lumens to judge how bright it will be.
Usually expressed on bulbs as lux (sometimes lumens and rarely as foot candles) All of these are measures of light output, more is better. But as was already mentioned, you need to consider the spectrum of light produced. Color temp and CRI are only indicators of spectrum. A bulb with a color temp of 5000K-6700K and a high CRI probably has to have fairly even distribution of light across the visible spectrum to get those numbers so that is good for plants. It's theoretically possible though that a lamp could produce a billion lumen of green light which would blind you but do absolutely nothing for the plants.

But it is simple for us viv folk. Just look for the brightest bulbs with 5000K - 6700K color temp and a high CRI. It's hard to go wrong that way.
 

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I though this might help to clarify color temps (Kelvin ratings). This is a picture of my hood. The Kelvin temps of the bulbs are:

6700 5500
9325 5500

 

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hehehe... I paid $200 for a self balasted mercury vapour bulb when I went moth collecting in French Guyana... My buddy bought a spare bulb just in case. One of them blew up few days after we got there it started to rain at 3am in the middle of the jungle. Fillament was still glowing extremely brightly, but there was no glass over it... It had a freaky purple/blue glow to it and was making a high frequency sound ...it was pure UV hitting our retinas... very very blinding and full of panic experience....ahh... those were the days :lol:



dmartin72 said:
I just refuse to pay $24 for a bulb! :shock:
 
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