Utah Reefs Homepage
  New Posts New Posts RSS Feed - what's a lux?
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

what's a lux?

 Post Reply Post Reply
Author
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Topic: what's a lux?
    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?

Edited by Amie - January 10 2008 at 3:00am
Back to Top
Adam Haycock View Drop Down
Guest
Guest
Avatar

Joined: August 23 2003
Location: Fiji
Status: Offline
Points: 2647
Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam Haycock Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 1:35am
Back to Top
Mark Peterson View Drop Down
Paid Member
Paid Member
Avatar

Joined: June 19 2002
Location: Murray
Status: Offline
Points: 21436
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark Peterson Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 8:48am

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
Back to Top
jfinch View Drop Down
Guest
Guest
Avatar

Joined: March 06 2003
Location: Pleasant Grove
Status: Offline
Points: 7067
Post Options Post Options   Thanks (0) Thanks(0)   Quote jfinch Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 9:06am

And most importantly... PAR.

Back to Top
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 9:25am
Originally posted by Mark Peterson Mark Peterson wrote:

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)

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? 

Back to Top
Adam Blundell View Drop Down
Presidency
Presidency
Avatar

Joined: June 24 2002
Location: Davis County
Status: Offline
Points: 18526
Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam Blundell Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 9:32am

Amie-
I have a lux meter you can borrow.  Let me find it....

Adam

Come to a meeting, they’re fun!
Back to Top
jfinch View Drop Down
Guest
Guest
Avatar

Joined: March 06 2003
Location: Pleasant Grove
Status: Offline
Points: 7067
Post Options Post Options   Thanks (0) Thanks(0)   Quote jfinch Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 9:33am

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.

Back to Top
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 9:48am
Originally posted by Adam Blundell Adam Blundell wrote:

Amie-
I have a lux meter you can borrow.  Let me find it....

Adam

Fantastic!  Thanks.

Originally posted by JFinch JFinch wrote:

Amie-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.

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?



Edited by Amie
Back to Top
Adam Haycock View Drop Down
Guest
Guest
Avatar

Joined: August 23 2003
Location: Fiji
Status: Offline
Points: 2647
Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam Haycock Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 3:26pm

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 ;)

Back to Top
bbeck4x4 View Drop Down
Guest
Guest
Avatar

Joined: June 22 2005
Location: Spanish Fork
Status: Offline
Points: 2378
Post Options Post Options   Thanks (0) Thanks(0)   Quote bbeck4x4 Quote  Post ReplyReply Direct Link To This Post Posted: December 05 2005 at 10:27pm
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
Back to Top
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: December 06 2005 at 12:46am
Originally posted by Adam Haycock Adam Haycock wrote:

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 ;)

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?

Back to Top
faviasteve View Drop Down
Guest
Guest
Avatar

Joined: June 30 2004
Location: Seychelles
Status: Offline
Points: 455
Post Options Post Options   Thanks (0) Thanks(0)   Quote faviasteve Quote  Post ReplyReply Direct Link To This Post Posted: December 06 2005 at 1:10am
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
Back to Top
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: December 06 2005 at 11:40am

Originally posted by bbeck4x4 bbeck4x4 wrote:

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

Are you using it?  Do you want to sell it?

Back to Top
bbeck4x4 View Drop Down
Guest
Guest
Avatar

Joined: June 22 2005
Location: Spanish Fork
Status: Offline
Points: 2378
Post Options Post Options   Thanks (0) Thanks(0)   Quote bbeck4x4 Quote  Post ReplyReply Direct Link To This Post Posted: December 06 2005 at 6:18pm
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
Back to Top
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post 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?
Back to Top
Adam Blundell View Drop Down
Presidency
Presidency
Avatar

Joined: June 24 2002
Location: Davis County
Status: Offline
Points: 18526
Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam Blundell Quote  Post ReplyReply Direct Link To This Post Posted: December 12 2005 at 11:19am

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!
Back to Top
jfinch View Drop Down
Guest
Guest
Avatar

Joined: March 06 2003
Location: Pleasant Grove
Status: Offline
Points: 7067
Post Options Post Options   Thanks (0) Thanks(0)   Quote jfinch Quote  Post ReplyReply Direct Link To This Post Posted: December 12 2005 at 11:35am

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.

Back to Top
Guests View Drop Down
Guest Group
Guest Group

Pet Store
Post Options Post Options   Thanks (0) Thanks(0)   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: December 12 2005 at 11:38am
Originally posted by Adam Blundell Adam Blundell wrote:

JON- do you think you need to filter UV light from pc bulbs?  I don't.

Adam

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) and I don't need to worry about Power Compacts unless the total wattage is above 400.

Thanks for ALL your help!

Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.281 seconds.