What % does egg crate block light

[matt2364]

I just installed two egg crate panels over my tank and not it is quite a bit dimmer. Just wandering if anyone has ever taken a lux meter and measured the difference with and without egg crate. Also, how much would some of those cheap reflectors help? I currently have 2x175w halides and 2x40w actinics on my 55 gallon. Should I move the light closer, they are probably 7-8 inches above the tank.

 

[matt2364]

Thanks in advance for everyones opinions.

 

[matt2364]

anyone?

 

[rebelprettyboy]

I cant give u a percentage, but ive never had a problem with my light being shaded cuz my egg crate...

 

[bang guy]

I just tested 2 areas in the tank with egg crate.
Under a 250 MH the lumens about 1/2 way into the tank went from 16,000 lux without eggcrate down to 14,500 lux.
Under VHO the lumens went from 4800 lux without eggcrate up to just over 5000 lux with the eggcrate.
?? Interesting...

 

[reefkprz]

Originally Posted by Bang Guy
http:///forum/post/2647923
I just tested 2 areas in the tank with egg crate.
Under a 250 MH the lumens about 1/2 way into the tank went from 16,000 lux without eggcrate down to 14,500 lux.
Under VHO the lumens went from 4800 lux without eggcrate up to just over 5000 lux with the eggcrate.
?? Interesting...
is your egg crate skinny side up or thick side up?

 

[bang guy]

Originally Posted by reefkprZ
http:///forum/post/2647939
is your egg crate skinny side up or thick side up?
Thick side up.

 

[reefkprz]

hmm. interesting.

 

[reefkprz]

what are the chances of you flipping the egg crate over and taking the same readings to see if it makes a difference?

 

[bang guy]

Originally Posted by reefkprZ
http:///forum/post/2648121
what are the chances of you flipping the egg crate over and taking the same readings to see if it makes a difference?
That shouldn't take too long.

 

[al mc]

Originally Posted by reefkprZ
http:///forum/post/2648121
what are the chances of you flipping the egg crate over and taking the same readings to see if it makes a difference?
If that result is repeatable I can see VHO lights coming with eggcrates attached in the future

 

[t316]

At the point of purchase, are they not labeled "LIGHT DIFFUSERS"? Think this might be for a reason??????????????????

 

[bang guy]

Originally Posted by reefkprZ
http:///forum/post/2648121
what are the chances of you flipping the egg crate over and taking the same readings to see if it makes a difference?
Flipped the eggcrate:
Under a 250 MH - 16,000 lux without eggcrate down to 14,500 lux with eggcrate.
Under VHO 4800 lux without eggcrate up to 4850 lux with the eggcrate.
One disclaimer - I have a really cheap lux meter that I vacuum sealed using a food sealer. At the high lux levels it's not precise so the high the Lux the higher the error amount could be. For the 16,000 Lux the error is + or - 250 lux. At 4800 the error rate is + or - 25 Lux. So, going from 4800 to 4850 may not actually be a change. It probably is though.
If you want to know, I only use this meter to test for when it's time to change my bulbs, nothing precise.
There, that's my disclaimer

 

[matt2364]

First off, thank you Bangguy for doing this for me. If I had to guess I would say mine dims down my light about 25% or so. Seems to make a huge difference when I take it off.
What color is your eggcrate? Mine is white, I was hoping to spray paint it black because it is the first thing you notice now when you look at my tank, bc I do not have a canopy. I just hope the black does not make it even darker since less light will be diffused off it.

 

[bang guy]

Originally Posted by matt2364
http:///forum/post/2651022
First off, thank you Bangguy for doing this for me. If I had to guess I would say mine dims down my light about 25% or so. Seems to make a huge difference when I take it off.
My eggcrate is white with a spattering of saltcreep.
I have a theory on the brightness of the tank. I noticed the same thing you did with the noticable difference in brightness. Much different than just a 10% drop in light would produce. In fact, I noticed a drop in brightness of the tank with the VHO even though the amount of light going into the water actually increased.
I think it has to do with the angle that the light is striking the water. Nothing conclusive but just me rambling. The eggcrate reflects the light down at a steeper angle than without eggcrate. Light that would be bouncing all over the tank is being pointed at a steep angle into the water. So, I think less light reflects out the front of the tank and that might make the tank look darker. Just a thought.

 

[spanko]

I did not do anything too scientific but just with what I saw the eggcrate trial I did, did not meet with my expectation. (little to no brightness drop) Instead I went to a pond supply store and bought a package of 3/8" pond netting. Then to Lowes for some plastic screen frame. Made the top on my tank from that.
You can see it in this picture.