what's a lux?
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Forum Name: Equipment
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URL: http://www.utahreefs.com/forum/forum_posts.asp?TID=9375
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Topic: what's a lux?
Posted By: Guests
Subject: what's a lux?
Date Posted: December 05 2005 at 1:10am
| Is there anyone out there that can explain to me what a lux is? It's not the same as Kelvin, is it? |
Replies:
Posted By: Adam Haycock
Date Posted: December 05 2005 at 1:35am
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Here you go... http://en.wikipedia.org/wiki/Lux - http://en.wikipedia.org/wiki/Lux ------------- 
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Posted By: Mark Peterson
Date Posted: December 05 2005 at 8:48am
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This is a very important topic and it should be moved to the Lighting section. We also need to discuss Lumens and Color Rendering Index (CRI) ------------- Reefkeeping Tips, & quick, easy setup tricks: www.utahreefs.com/forum/forum_posts.asp?TID=9244 Pay it forward - become a paid WMAS member 
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Posted By: jfinch
Date Posted: December 05 2005 at 9:06am
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And most importantly... PAR. ------------- Jon https://www.youtube.com/channel/UC6y_EzjI_ljbIwf2n5uNzTw" rel="nofollow - What I've been doing... |
Posted By: Guests
Date Posted: December 05 2005 at 9:25am
I knew someone was going to say that. I put it in this section because I am trying to build something that is not fish related. I am trying to design a light box for someone that has Seasonal Affected Disorder (SAD). The person is suppose to sit 20" away from lights that are 10,000 lux for 20 minutes a day. Is there someway to measure the lux of a light at a given distance? |
Mark Peterson wrote:Posted By: Adam Blundell
Date Posted: December 05 2005 at 9:32am
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Amie- Adam ------------- Come to a meeting, they�re fun! |
Posted By: jfinch
Date Posted: December 05 2005 at 9:33am
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Is there someway to measure the lux of a light at a given distance? Yes. Get or borrow a lux meter (photographers use them). A 250 W MH bulb has an intensity of about 24,000 lumen. Spread all that light out over 2 meters and you would have 12,000 lux. ------------- Jon https://www.youtube.com/channel/UC6y_EzjI_ljbIwf2n5uNzTw" rel="nofollow - What I've been doing... |
Posted By: Guests
Date Posted: December 05 2005 at 9:48am
Fantastic! Thanks.
Sounds like a good reason to get a MH on my tank. |
Seriously though, is there a distance that you could sit from your tank and the lux would be 10,000? I guess the hood of the tank would have to be up, right? Would a 125 W MH mean that you would only have to be 1 meter away to get 11,000 lux?Posted By: Adam Haycock
Date Posted: December 05 2005 at 3:26pm
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Amie, does it say anything about what color of light to use? Id would think a 6500K metal halide would be perfect for that. Hmm maybe a good excuse to buy a pendant for a new frag tank ;) -------------
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Posted By: bbeck4x4
Date Posted: December 05 2005 at 10:27pm
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we have a box that is supposed to be used for SAD it has two 65 watt f40bx/spx41/rs bulbs in it, that would be a 4100 k bulbs Brian ------------- Family Portraits /Google trusted Photographer for Google Maps for Businesses |
Posted By: Guests
Date Posted: December 06 2005 at 12:46am
The only information I have been able to find states that the light needs to be 10,000 lux at 12", properly screen out UV wavelengths, and preferably have a broad spectrum of color. ( I guess the color doesn't matter as much.) I think the idea is to simulate sunlight. Is a 6500 K light 'whiter' or more yellow than a 10,000 K light? |
Posted By: faviasteve
Date Posted: December 06 2005 at 1:10am
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6500 K is more yellow than 10,000K so it isn't as pretty on a reef tank but the the Iwasaki 6500 K simutates natural sunlight at the surface better than any other metal halide so it should be a super SAD bulb. Anything between 4000 K and 10000 K is probably OK. ------------- Steve Burton Logan, Utah |
Posted By: Guests
Date Posted: December 06 2005 at 11:40am
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Are you using it? Do you want to sell it? |
Posted By: bbeck4x4
Date Posted: December 06 2005 at 6:18pm
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we are using it with a timer to have the daylight (simulated) occur at
6:00 am, so far its working pretty good, I was having trouble with
staying asleep at night. Brian ------------- Family Portraits /Google trusted Photographer for Google Maps for Businesses |
Posted By: Guests
Date Posted: December 12 2005 at 11:16am
| Thanks to Adam letting me borrow his lux meter, I was able to test different lights. I found that a 55 Watt 10,000K power compact emits 10000 lux at 20 inches. Now I just need to figure out the UV issues and I'm set. I assume that I can just get a piece of UV protective glass from a glass company? |
Posted By: Adam Blundell
Date Posted: December 12 2005 at 11:19am
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Yes, but I would get a piece wide enough to cover two bulbs. After using that glass you will lose a lot of your light and may need to use two 55 watt bulbs. JON- do you think you need to filter UV light from pc bulbs? I don't. Adam ------------- Come to a meeting, they�re fun! |
Posted By: jfinch
Date Posted: December 12 2005 at 11:35am
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do you think you need to filter UV light from pc bulbs? I don't. I doubt it too. I'd use the bulbs as is. ------------- Jon https://www.youtube.com/channel/UC6y_EzjI_ljbIwf2n5uNzTw" rel="nofollow - What I've been doing... |
Posted By: Guests
Date Posted: December 12 2005 at 11:38am
You are right, Adam... I went back and reread the article you sent me on UV Radiation ( http://www.advancedaquarist.com/issues/aug2004/feature.htm - http://www.advancedaquarist.com/issues/aug2004/feature.htm ) and I don't need to worry about Power Compacts unless the total wattage is above 400. Thanks for ALL your help! |