Effects of various aquarium covers on light transmission

[Jeto2004]

Nice write up, very helpful! I assume that the glass was spanking clean for observed 12% reduction. Any chance you used glass that has some salt spray on it for "real" life situation?

 

[andrewey]

@Dana Riddle, I don't know if you have any available, but have you tested clear mesh netting (1/4")? The last time I tested it on my setup, I only had a ~4% reduction in Par (if my memory serves correctly). I know you're busy and the question might not be very interesting, but if you are interested in further experimentation and don't have any available, I could ship you some. I believe jda observed a ~2% reduction in par with 1/2" clear netting.

 

[blasterman]

I use glass tops on all my tanks and measured it with s spectrometer sone years ago.

Standard intensity loss dry was rather trivial. Maybe 6%, and most of that was in the orange red area due to the iron in the glass. Acrylic was better, but acrylic sags after awhile.

The problem with glass is condensation and water drops build up which further reduces intensity often more so than the opacity of the dry glass. Mesh doesnt have this issue. Since I have light to spare and intensely dislike evaporation and dont trust ATOs this doesnt bother me. Clear mesh though seems the best compromise.

Theres always metalized egg crate, but its exoensive.

 

[Dana Riddle]

@Dana Riddle , when I get my new tank up and running, gonna be awhile, I plan on adding a Octo Lids top, if you have the time maybe you can come over and do test on it.

Sounds like a deal, Bill!

 

[Dana Riddle]

I have wondered the effect of condensation on glass lids.

Could happen. I think dust and salt creep are more of an issue though. Dirty glass eats up about 10% based on testing I did back in the 90's.

 

[Dana Riddle]

I use glass tops on all my tanks and measured it with s spectrometer sone years ago.

Standard intensity loss dry was rather trivial. Maybe 6%, and most of that was in the orange red area due to the iron in the glass. Acrylic was better, but acrylic sags after awhile.

The problem with glass is condensation and water drops build up which further reduces intensity often more so than the opacity of the dry glass. Mesh doesnt have this issue. Since I have light to spare and intensely dislike evaporation and dont trust ATOs this doesnt bother me. Clear mesh though seems the best compromise.

Theres always metalized egg crate, but its exoensive.

Good observations! I will add that I tried metallicized egg crate years ago, and apparently the salts it was exposed to caused the coating to peel off. This has been 25 years ago, and perhaps an improved material is on the market today.

 

[swiss1939]

Good observations! I will add that I tried metallicized egg crate years ago, and apparently the salts it was exposed to caused the coating to peel off. This has been 25 years ago, and perhaps an improved material is on the market today.

Possibly try one of these. They are a bit more expensive but are made for lighting. Not sure how they would hold up for use near salt.

Kino Flo Eggcrate Louver for Image 40 (Silver)

Buy Kino Flo Eggcrate Louver for Image 40 (Silver) Review Kino Flo null

www.bhphotovideo.com

You can get these in different sizes based on the lighting fixtures they are made for.

 

[Dana Riddle]

I use glass tops on all my tanks and measured it with s spectrometer sone years ago.

Standard intensity loss dry was rather trivial. Maybe 6%, and most of that was in the orange red area due to the iron in the glass. Acrylic was better, but acrylic sags after awhile.

The problem with glass is condensation and water drops build up which further reduces intensity often more so than the opacity of the dry glass. Mesh doesnt have this issue. Since I have light to spare and intensely dislike evaporation and dont trust ATOs this doesnt bother me. Clear mesh though seems the best compromise.

Theres always metalized egg crate, but its exoensive.

How did you measurement light intensity? Lux? PAR?

 

[Ketan]

I think there could be a middle ground where the middle sections of egg crate is cut and the thinner netting is glued in those areas. The egg create would just be for support at this point.

 

[rennjidk]

I got a private message from GaryE and thought my reply might be of interest to others. Here’s the message:
I know you have done innumerable studies on the various different lighting packages available. Have you ever studied the effects of different coverings on PAR levels?

Specifically, I'm interested in the difference between glass top vs egg crate vs mesh type screens.

I started my tank with the standard glass tops that came with it and decided that I wanted to go to something more open, so I went open top for a while. I had a very nice little hawk go carpet surfing, so that was a bad option. I have since moved to egg crate (white plastic) and am not real excited about the amount of loss I can perceive. Just to the naked eye it seems to be quite a bit of drop in light level. Whether this is just a loss of spread or actual loss of PAR I don't know as I don't have a par meter to check.


Thoughts?
My reply:
This took a bit of lab work using an Apogee MQ-510 quantum meter and a ‘globe’ Cree 6500K LED as the light source.
Eggcrate material: There is ‘good’ eggcrate and ‘cheap’ eggcrate. Good eggcrate has a ‘thick’ side and a ‘thin’ side – this acts as a parabolic lens and can concentrate light. I wrote an article about this for FAMA in the late 90’s and found if that orientation could focus point source light as much as 25% - of course, there is a reduction in light outside of the focus area. I do not have ‘good’ eggcrate anymore - the stuff being sold in big box stores is the ‘cheap’ stuff. However, if you’re fortunate to have quality eggcrate – and if memory serves – light will be focused if the thick side is up.
I have only ‘cheap’ eggcrate, but found there is a difference between white and black material
Black eggcrate reduced light intensity by 20%, while the white by only 12%.
Glass: I used a glass cover made for an aquarium, maybe 1/8” to 3/16”. Light intensity was reduced by 12%. Bear in mind glass will often transmit ultraviolet radiation. Not much of an issue if you’re using LEDs, but could be if you’re using a metal halide lamp.
Acrylic (thin and thick pieces): Light reduced by 12%. Acrylic will absorb UV and will eventually yellow and possibly disintegrate (if it is thin.)
Fiberglass window screen material: Reduced light by 44%.

Does that 12% reduction through glass take into account condensation which forms almost immediately, or was this through a freshly cleaned glass canopy?

 

[oreo54]

Does that 12% reduction through glass take into account condensation which forms almost immediately, or was this through a freshly cleaned glass canopy?

Dirty, condensation, or clean data I've seen shows it makes little difference...
From above

Dirty glass eats up about 10% based on testing I did back in the 90's.

Also

Dispelling the myths about glass lids on reef aquariums.

People in the hobby often repeat what they hear others say- - “Glass lids Are bad. They get dirty and block a lot of light” - “Clean glass drops PAR 10-20%. On top of that, the dirt, salt creep and humidity drops cut par an another 10-15% so you have to increase your lights every week to...

www.reef2reef.com

Dirty glass isn't as clear as condensation.

What I'm going to suggests is that even a "dirty" glass top doesn't significantly reduce the lighting levels when you consider other sources of light loss.

Light Loss through Glass and other Musings

 

[flagg37]

I measured a 20% reduction when going through a 1/2” thick piece of Starphire glass. I thought that was a lot but seeing that you measured a 12% reduction going through 1/8” glass that’s not too bad.