Marine Depot Forums / TEAM Marine Depot / Marine Systems and Husbandry – by Anthony Calfo / Egg-grate/egg-crate/Lighting grid over aquaria / Latest Posts

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Tue, 28 Mar 2006 22:12:53 GMT

heehee... I agree that we still differ And I don't think part of it is a matter of perception or definition. There is either more light entering the aquarium and reaching the targeted animals or there is not. This is about as black and white as it gets. My assertion is that with a grid under light systems that have spreading light (because of reflectors, lamp styles... whatever), there is simply more light making it into in the aquarium where we want it overall. Net gain is my mantra here

My favoritism for moving light points/systems actually does not come into play versus the grid issue since a principal purpose of the former is energy efficiency (using less lamps/less watts) by exploiting directional lighting while in the case of the latter we are all about capturing the greatest quantity of light from traditional lighting (read: less energy efficient static sources). Its apples and oranges.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Tue, 28 Mar 2006 16:49:45 GMT

We continue to differ, perhaps as a matter of definition, on the efficiency question and as to whether there's an overall net increase of light entering the aquarium with the eggcrate in place. Certainly there is more light within the orange region depicted above. Would you agree that adopting Sanjay's "Total Incident Par" technique and measuring a grid of points within both the yellow and orange regions shown in the diagram above gives an adequate answer as to the overall efficiency/net increase question?

That aside, you raise another interesting point. For there to be the light increase shown in the orange region, light has to be traveling at an angle through that point. That suggests that the eggcrate will result in more side-lighting of objects in the tank than the primarily vertical lighting produced by parabolic reflectors. If I infer correctly from my reading of your numerous posts about light rails, that'd be a good thing.

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Tue, 28 Mar 2006 12:36:29 GMT

excellent, Mark. Thanks bro! Much clearer... and surely more helpful to the public reading the thread.

I do agree with your model overall but must re-emphasize that the reality is not so abolute (not a matter of darkness and blinding bright in loss/gain regions). For most systems, the grating is an improvement. That is to say, most aquarists have featured animals in focussed places. And... most aquarists have garden reef aquaria with a very unnatural mix of corals... most of which can find a better place in this wider range (intensity) of light than under the dreadfully standardized (and less efficient) scheme of spread without the grating material. As an example... the typical reef aquarium with a colorful shallow water Acro and some deeper water X (mushrooms, brain coral, large polyp zoanthid species) will fare better for having this range rather than (without grating) the corallimorphs or red brains getting too much light while the shallow water Acros shed colorful FPs for having less/inadequate light.

And there is still the benefit of a net gain overall of light that makes it into the aquarium. My assertion above is that this is best for most aquarists. An exclusion would be a heavily stocked (re: surface areas utilized) biotope tank with compatible like-needs animals. In this case, the focus of light and greater contrast in intensities in different spaces does not serve the needs here (read: lose the grating! )

Indeed, most folks do not have biotope tanks or even remotely natural mixes of corals that can thrive under a standarized lighting scheme.

But yes, we do come back to knowing your animals needs, making the best/most compatible mix... and testing before flying

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Tue, 28 Mar 2006 12:13:38 GMT

...do consider that people will read your statement to mean (literally) that if they add the grating, they will have less than 20% of the coverage they had versus without the egg grate

Well that's not what I was saying/meant at all. (These conversations are so much easier over a table when you can scratch things out on a napkin and not abbreviate the explanations. With you planning on being only a few hours away in Toronto a few days from now, I'll have to see if I can make it up there... napkin in hand.)

An electronic version for now:

The black outlines show typical tanks with widths of 12" and 18". The yellow region is the intended "coverage area" of the bulb... in other words, we want the bulb to provide light to this area of the tank. (This acknowledges your point that we're not typically stocking things to the walls of the tank). The 12" tank depicts a 2" border, the 18" tank depicts a 4" border.

The orange region is the approximate area that will receive increased lighting, if eggcrate is present, according to Dana's graphs. Also from the graphs, the remainder of the yellow area receives less light than when the eggcrate is not present. Depending upon how you stock things, that could be a good or bad thing.... we're back to the standard recommendation: know, test and adapt your setup for your specific inhabitants.

Brian, thanks! For the light levels to be increased directly under the bulb, there have to be light rays travelling at an angle towards the center. It would be interesting to have high, middle, low numbers to see if the pattern stays the same with depth (though at reduced intensities).

A very interesting discussion....

Anthony, a PM on the berghias to follow shortly...

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

BrianPlankis — Tue, 28 Mar 2006 11:47:15 GMT

Mark (3/27/2006)

October 2000 FAMA

Brian, if you have time to take some additional measurements, I'd be interested to know if your results vary with depth?

- Mark

Mark,

I did take measurements at different depths, I don't have my numbers in front of me, but at 2" underneath the water surface directly under the bulb was the largest increase (I think around 25%), but there was a net gain in intensity, decreasing with depth, all the way down to just above the sandbed, again directly under the bulb. The largest loss of intensity was 12" horizontally away from the point source of the bulb and 2" under the water surface. This makes sense since a lot of the light would be hitting the vertical portions of the eggcrate trying to reach that spot.

I'm planning on a lot more measurements in the future, but time is the limiting factor right now.

Brian

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Tue, 28 Mar 2006 09:43:15 GMT

fabulous input, alsonotlefthanded! This is very much appreciated... and agood constructive dialogue overall.

Mark... we disagree on a number of points still (your math/assumptions and definition of target area, eg... not all aquarists stock their tank to within 5 cm of the walls. Not even close). But do let me ferret Dana's article and more to try clarify my point/perspective before asking you to clarify yours.

Without keeping you/others in suspense though... the "reduction of coverage by ~80-90%" is incorrect from my position/perspective. Have you personally taken readings yet with a meter to verify your math/numbers? Respectfully asked here (not barking). But do consider that people will read your statement to mean (literally) that if they add the grating, they will have less than 20% of the coverage they had versus without the egg grate. Yet how again is this possible with a material that blocks a fraction of the surface area (and is not shaped like a funnel )?

[PS - I've been meaning to ask you how your Berghia are coming along? Do PM if you have the time ]

RE: Egg-grate/egg-crate/Lighting grid over aquaria

alsonotlefthanded — Tue, 28 Mar 2006 06:51:29 GMT

I can't resist passing along some great info on T5 lamps that was originally posted by "The Grim Reefer" on RC. He now frequents this board, at least in the lighting area, so I hope he doesn't mind me quoting. His T5 PAR data is just so nice to have. In addition to giving us a measure of PAR over depth numbers to create a proper graph of the degridation, I think the results paint a better picture for T5 lamps.

For what it's worth in each of those threads he compared his new T5 setups to PC and/or MH bulbs he had on hand, but they were old bubls compared to new and I'm not quoting that information because I don't want to distract from the T5 message.

I'll also mention one issue I struggle with, it's that T5's are not so much a single point source, as much as they are a line or bar, so the high PAR ratings cover a different shaped area then with MH. It'd be great to see that data mapped out they way Sanjay does it on a nice grid. I *believe* Grimm did the first test by measuring in the middle of the center two bulbs rather then directly under a lamp as he had 4 bulbs spread across 18" top of his tank; if that's the case it makes the numbers very respectable.

To jump right in what follows is the highest output T5 setup:

"Icecap 660, SLR reflectors, 2xBluePlus, 1xGE 6500K, 1xAquablue (all 48") - bulbs 1 month old.

0" - 810
1" - 745
2" - 680
3" - 640
4" - 600
5" - 550
6" - 500
8" - 430
12" - 320
16" - 240
20" - 185
24" - 150 *I suspct he didn't adjust for the depth of instrument, so more like 23"? "

His ballast data: http://reefcentral.com/forums/showthread.php?s=&threadid=732591

"18" from the surface of the water to the sandbed, or at least to the sensor on the sandbed. Now that I think about it the lights were about 3" above the water for the test."

Dynamic Spec T5 ballasts
Wattage used 232
PAR Produced at Sandbed 135
.58 PAR per watt used

Ice Cap 660
Wattage used 303
Par produced at sandbed 183
.6 PAR per watt used>

He also did work on Reflectors: http://reefcentral.com/forums/showthread.php?s=&threadid=536358

"This was with a single lamp shooting through 2 panes of glass in addition to the 24" of water. This test I used an actinic lamp. Had the same differences using the sun but I can't for the life of me find the darn numbers from that lamp.

Ice Cap Solid 31 umol
Brand X 29~30
Tek 25~26"

In tank test were done in the 125 with the sensor 18" below the surface with the lamp about 1 1/2" above the water. In that test the Ice Cap and Brand X reflector were tied with the Sunlight Supply Tek coming in about 10% lower. On the 24" test the Ice Cap just nudged out Brand X with the Tek starting to suck wind at about 20% less."

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Mon, 27 Mar 2006 21:52:01 GMT

October 2000 FAMA

I remember running across that citation... not one I happen to have in my collection or was able to find online.

The charts are interesting, thanks for posting them. Couldn't help but grab the calculator and do some quick figuring. The lower chart shows an area around 25sq inches or so in size in which the light levels are increased. The remaining area shows decreased levels of light.

A common recommendation is to have one MH lamp for every 2 feet of tank length. Based on that recommendation and the charts above, folks using eggcrate are going to see a decrease of light in 90% or more of the coverage area of the bulb: 12" x 24" = 288sq in. (288-25)/288 = ~91%.

It helps a bit if we assume we're not trying to light a 2" border of the tank on three sides since that reduces the coverage area by 112" to 176sq in. But we'll still have a decrease of light in more than 86% of the target area: (176-25)/176 = ~86%.

Brian, if you have time to take some additional measurements, I'd be interested to know if your results vary with depth?

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Mon, 27 Mar 2006 20:53:11 GMT

October 2000 FAMA... article by Dana. I've carried the citation but its been a long time since I've read it.

Outside of this article, I don't recall Dana being especially pro or against the use of egg-grate FWIW

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Mon, 27 Mar 2006 17:38:23 GMT

Anthony,

Did Dana say how far below the eggcrate he took his readings or if he tried different depths?

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Mon, 27 Mar 2006 17:01:12 GMT

excellent info Brian... muchas gracias for sharing.

In this/all cases there are mutiple variables nearly competeing with each other you might say. For example... having a better canopy but a glass cover, no glass cover but aged lamps, great reflector but high lamp placement... and various permutations of these examples and more.

Some additional comments (by me) here:

in practical applications, eggrate has a greater impact on MH lamps versus flourescent

eggrate indeed does increase light under the focus area, in part, by channeling stray/horizontal light (the essence of our thread here and usually a good thing for aquariums as they are most all fairly narrow in width)

a jpeg from Dana Riddle detailing this observation is above.

Since most all of us also have our featured corals in focussed areas (the literal handicap of a rockscape that must be away from the walls of the aquarium), we benefit by this net gain of focussed light under eggrate. FWIW... Dana has recommended the egggrate be about 3" below the lamp.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

BrianPlankis — Mon, 27 Mar 2006 11:58:51 GMT

Anthony,

I took a few quick readings this weekend and got some suprising results with eggcrate.

First off, my tank has a canopy with a reflector used by both the MH and VHO bulbs, pretty inefficient from what I hear. There is very little light spillage when the canopy is closed. I took readings using the apogee meter with the sensor tipped approximately 45 degrees toward the light source just outside my tank at the bottom, 12" away and 24" away from the tank. The PPFD readings were really insignificant (1-3 PPFD). I then put the eggcrate on the tank (approximately 1" above the surface of the water, resting on the plastic frame on the top of the tank and the glass center brace) and the readings outside the tank remaining unchanged except for at 24" away from the tank it dropped from 3 to 2 PPFD.

Inside the tank with the eggcrate on I did see a significant increase in intensity (15-25%) directly underneath the SE MH light bulbs, but farther away light intensity was decreased, by as much as 50%. It would be interesting to see if I moved my VHO lights down properly if the light intensity would increase some, but I don't have the time to do that right now. I still have an ASM G2 sitting next to the tank ready to go and that takes priority

Brian

RE: Egg-grate/egg-crate/Lighting grid over aquaria

BrianPlankis — Fri, 24 Mar 2006 21:08:13 GMT

Anthony Calfo (3/24/2006)

because of my animate nature/personality and flare for a good narrative, if I may say so, folks often think I'm simply being dramatic when I tell them to just unplug their flourescents (the way most are moutned and maintained) unless they are purely employed for aesthetics. I sometimes remember to say... "Don't just take my word for it... get a light meter."

Thank you for getting a light meter Brian and sharing your observations

Your welcome Given my love of data points, there are a lot more observations coming Getting back to the topic of this thread, up next is egg crate.

Brian

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Fri, 24 Mar 2006 20:53:55 GMT

Thank you for getting a light meter Brian and sharing your observations

RE: Egg-grate/egg-crate/Lighting grid over aquaria

BrianPlankis — Fri, 24 Mar 2006 15:54:34 GMT

A very interesting thread. I finally broke down and purchased a Apogee meter. I received it last week and I'm definitely going to be lowering my VHO when I get a chance. Because of the reflector they are mounted 8" above the water surface and the light meter reveals the truly dismal story. Without my MH lights on (only VHO actinic) my PAR (PPFD) values from the meter are:

1" from the bulb - (around 300-400) (Granted these are 10 month old bulbs)

6" from the bulb - 42-95

10" from bulb (2" under water) - 28-50

14" from bulb (6" under water) - 24-38

20" from bulb (12" under water) - 24-33

They are obviously just for looks at this point

Brian

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Mon, 27 Feb 2006 14:30:39 GMT

IMO PAR versus LUX is a big deal. You can have a light that produces a high LUX reading, but is otherwise completely useless for growing zooxathellate corals for having a low PAR value.

PAR is the way to go.

As for melting, yes... it can melt indeed so close to the halide. Just like the tank bracing we hear of on acrylic tanks with halides mounted too close. But the flaw is not the egg-grate, the fault is the application (placement of lights too close to plastics). In this case, your light canopy is not very deep and this may be good or bad. It's good if you want spread of light, its bad if you want focus. If seeking the latter, you may need to build a collar for the canopy box to get better focus from your reflecter and/or use of egg-grate

RE: Egg-grate/egg-crate/Lighting grid over aquaria

clownfish4 — Fri, 24 Feb 2006 19:42:02 GMT

Anthony, does the egg-grate melt readily? I have a 60g tank acrylic tank, 24x24x24, with a 175w MH about 1-2" from the top of the tank. I want to put egg grate on because if a fish jump it will land on top of the acrylic and will eventually die. So my question is will the egg-grate melt an inch below a 175? If so, will a fan completely prevent it? I can't raise the halide any further....

RE: Egg-grate/egg-crate/Lighting grid over aquaria

captbunzo — Fri, 24 Feb 2006 12:48:51 GMT

A lux meter is going to be more or less sensitive to light each wavelength. The peak wavelength is going to be the wavelength of light to which the meter is most sensitive. And I suspect that sensitivity is going to go down as you get further from that wavelength in some sort of curve. The range of measurement is a setting on the meter that changes the sensitivity of the meter. If you are measuring dim light, you'd use the 0-1999 setting. Brighter and you'd go for 2000-19999. And for the brightest light measurement, you'd go 20000-50000.

As for LUX vs. PAR. From what I have read, PAR is simply a narrowing down of what LUX is measuring. LUX is providing some sort of "total light" measurement. PAR is specifically a measurement of the Photosynthetically Active Radiation (light) available. That is, btw, what PAR stands for. And that's also all that I know on the matter.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

clsanchez77 — Fri, 24 Feb 2006 11:59:14 GMT

Milwaukee Lux Light Meter

Specifications:
Range 0.000 - 1999 Lux
2000 - 19999 Lux
20000 - 50000 Lux

Range setting Manual through key buttons
Resolution 1 Lux
10 Lux
100 Lux

Accuracy ± 6% of reading ± 1 digit
Peak wave length 560 nm
Sensor type Silicon Photodiode
Sensor sensitivity 100 scotopic LUX
Sensor stability ± 2% change per year (in the first two years)
Battery/Life 1 x 9V/150 hours continuous use
Environment 0 to 50¡C; RH 95%

This may be an ignorant question (these are always good ) what is meant by the peak wave length is 650nm & what is the range of measurement. How is LUX related to PAR/PPFD (w/sq.m.?)

If this device is suitable as close-enough, it is a viable option for me IMO.

Chris

RE: Egg-grate/egg-crate/Lighting grid over aquaria

captbunzo — Fri, 24 Feb 2006 11:45:19 GMT

Required equipment list? Is this where someone says: If you spend thousands of dollars on a reef tank, what's $300 or so on a PAR meter?

Seriously, there is a point to that. However, the real point of this post is to toss out the suggestion of getting a LUX meter as a makeshift solution. From what I can tell, they will do reasonably well measuring what we need to measure (in this thread) and will cost a LOT less.

http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MIL-SM700&Category_Code=

The one at that link is only $70. And it's peak wavelength is 560 nm, which is smack-dab in the middle of the range of Photosyntheticly helpful wavelengths. I can probably pull of spending the $70 on one of those eventually. The PAR meter will likely always remain a dream.

Anthony, etc, people who know more about this then I do.... Is this a reasonable suggestion? I got this from an article posted on Reefkeeping.com by Eric Borneman.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

clsanchez77 — Fri, 24 Feb 2006 11:13:09 GMT

Definite Maybe.

I really want the meter but am hesitant to spend the money when I can use it for something else on the tank. Not knocking the light meter, but in my book it goes in the wish list and not in the required equipment list.

Having said that, does anyone in the south Louisiana/Mississippi area have one? I'd be willing to 'rent'.

This is something I will buy...but just seems I should focus my money now getting the tank setup...tunze style...tough decision.

Chris

RE: Egg-grate/egg-crate/Lighting grid over aquaria

DonJasper — Fri, 24 Feb 2006 10:38:30 GMT

jolt_26 (2/23/2006)

can i tilt my parabolic reflector (for T5) a little bit so that it would point to the center? so instead of losing light to the air, i would actually focus them back on the tank.

A light meter measurement will remove all doubt. Without a measurement then the best that anyone can say is "Maybe".

RE: Egg-grate/egg-crate/Lighting grid over aquaria

jolt_26 — Thu, 23 Feb 2006 07:55:36 GMT

can i tilt my parabolic reflector (for T5) a little bit so that it would point to the center? so instead of losing light to the air, i would actually focus them back on the tank.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Fri, 03 Feb 2006 17:18:54 GMT

agreed, bro. And I must admit that while technology appeals to me (bells and whistles), hard science often does not... at least not for its intrinsic value alone when not applied. I am a practical man if nothing else

It really is good enough for me to see (and measure) more light making it into my aquarium for placing an engineered grid between the light and the water surface. I don't need to know how/why.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Fri, 03 Feb 2006 16:47:54 GMT

I may well be completely ignorant or simply daft here...

I think I've known you long enough to know that you are neither of those. I however, may have to apply for the position... depending how this works out.

To be fair, my original estimate was "20-50%"... showing the area blocked by the top of the grid to be 14-19% was meant to show that the blocked light starts at levels near 20% and goes up from there.

I really have no reason to question either your or Don's results, just lament that in Don's case, I'm unable to reconcile why his results would differ from Sanjay's. Regardless, this has crossed the line into "mental masturbation" so I'll defer further comment until the opportunity for a more scientific investigation presents itself or some epiphany occurs that reveals the error of my ways.

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Fri, 03 Feb 2006 16:26:34 GMT

I may well be completely ignorant or simply daft here... but I still do not understand or accept the contradictory perspective/explanation of the physics here. I will be content to be proven wrong as much as right.

But regarding the explanation of "how did 50% of the light get reduced by use of a grid"... the above post in reply begs the question in my mind that by the math offered, can the white material of the gird itself really be absorbing 31% of the light? If 14% is blocked and 5% is reflected (but not beyond the grid/into the aquarium), then is the remaining 31% of "lost" light truly being absorbed by the surface of the grid by virtue of its color alone (regardless of the type of reflecter used above the lamp)?

And if we take that same lamp and reflector (or not) and simply take the grid away, will there be a 50% increase in light?

Nope. I don't see it.

And so, this is the issue we keep getting back to IMO. What is the net gain of light in typical/practical aquarium applications!

It's my assertion that the average hobbyist with a light fixture mounted in such a way that light can be seen spilling outside of the aquarium will acheive a net gain in light by using a common egg-grate/egg-crate the way it is described in the first post of the thread.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Fri, 03 Feb 2006 16:07:19 GMT

Mark offered the following explanation about the reduction of light. I'm not sure where he got this from though and will ask here if he can clarify it when he has the time:

---------------

Mark wrote:

You asked, twice, in the thread "how is it that a diffuser grid whose intersecting partitions are a tiny fraction of an inch with a sum total of mere single digit(?) percentage of the surface area obstructed can block 50% of the light?"

----------
The part of this that wasn't initially obvious to me was how much area the grid itself takes up. The midlines of the grid of my eggcrate are .71" apart, making the area of a single grid .5041 sq in. The thin part of the eggcrate grid that frames that area (1/2 of the .05" width) takes up 14% of that area. The wide part (1/2 of the .07" width) takes up 19% of the total area.

So, if a reflector was able to direct all the light directly down into the tank, the thin flat top part of the eggcrate would block 14% of the light and an additional 5% would be reflected off the curved/tapered sides.

The additional loss of light comes from the fact that the eggcrate does not have mirrored surfaces (so light is absorbed by the eggcrate) and the fact that light leaving a round bulb does so at the angle of the bulb's surface. So much of the light that would fall between the bottom of the reflector and the surface of the tank will end up striking the eggcrate, resulting in some being reflected in the tank, some not, and some being absorbed/lost.

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

DonJasper — Fri, 03 Feb 2006 15:51:24 GMT

http://www.marinedepot.com/FORUMS/FindPost24617.aspx

Please note that both Anthony and I have measured results. He with egg-crate and me with wood.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Fri, 03 Feb 2006 14:30:02 GMT

Go back to the observation that a light bulb on wood has measurably more light output than the same light on a mirror.

Don, while I immensely enjoy your style of writing, I'm not really sure I understand what you're saying?

But, I don't think you mean to imply that wood works nearly as well at getting light into our tanks as a well designed reflector does. From Sanjay's article cited earlier:

http://www.advancedaquarist.com/issues/mar2003/feature.htm

"As can be clearly seen from the data, having any of the above mentioned reflectors is better than just having a painted hood.."

Best,

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

DonJasper — Fri, 03 Feb 2006 12:40:53 GMT

Mark (2/2/2006)I suspect that Andy and Anthony are not far apart on this at all. Both, I suspect, would agree that you get more light if you use a good reflector and no egg-crate/louver.

Go back to the observation that a light bulb on wood has measurably more light output than the same light on a mirror. Same principle applies. I've not done it, but I doubt you could measure the difference in the light output from a bare bulb, then seen straight through egg-crate.

But if 'look up' from the bottom of the tank you'll see a tiny bright spec, and then the darkened inside of the canopy. Can we improve on this? How about taking some of the light invisibly streaming sideways destined to light the carpet and redirect it? A piece of egg-crate louver would been seen 'glowing' viewed from the tank, powered by the carpet-bound light. This is in effect redirecting the light to the tank bottom, that's why the louver appears to glow when you look at it.

If you really cared about getting the most out of every last photon, you'd hang the bulb from the ceiling on a wire to light the room. There's still a loss with reflectors. That's not the point of aquarium lighting. We want to get as many photon's in the tank as possible, and if that means we light the room less efficiently - so what?

What's really a mind-bender is the fact that many headlights have a reflector blocking direct viewing of the light bulb. This reflects all light streaming forward and sends it back into the parabolic rear reflector. So taking light destined to light the sideway and via-two reflectors sending it forward - and on balance you get a net gain of light where you want it.

http://www.alplighting.com/Plastic/Index.html

NOTE: Hey I love DIY improvisation - taking something built for the purpose of influencing fluorescent light and getting a two-fer benefit for reef keeping. I had no idea that egg-crate would be sided. But given that there's different flavors of 'egg-crate' which one is the Best Why stop there? How about if we took additional measures to increase the 'glowing'. Maybe lay some of the clear textured lens on top of the egg-crate - cutting a hole to let the direct light to shine straight through? Or glue zillions of tiny mirrors - one for each hole in the egg-crate not in the direct path of the light? Humm. Guess I'd better buy another bag of hot-glue sticks.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Steven Pro — Fri, 03 Feb 2006 04:36:30 GMT

The thing to remember when looking at lighting industry data versus aquarium applications is the lighting people install the eggcrate with the fat side up so they block and diffuse light whereas we install the thin side up so it focuses light down into the tank versus spreading out and lighting the surrounding floor.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

captbunzo — Thu, 02 Feb 2006 23:37:15 GMT

Wow. I go away for a day and this leads to all sorts of interesting discussion.

I have been working out some plans concerning how exaclty one would run a good scientific test. So far, all we know is that it is going to be fun and take quite a bit of time to go through several iterations. Anyhow, I also wanted to state that this is going to be my last post in this thread until I have aquired a light meter and can make final preperations for the test. However, here is a teaser.....

So far the test will work as follows:

1. Stay up late and turnoff all room lights. Always a good first step, eh? The purpose of this is to avoid any interference light.
2. Map out locations for readings. This will include regular positions inside the tank (at different x,y, & x coordinates, spaced out at 6 inch intervals). This will include similar points above the tank, out of the water. These points will range from right above the waters surface, up to as high as we can measure. The interval will drop to somewhere between 1-3 inches. The more, the better. And lastly, we will test some points out of the tank, measuring how much light is escaping.
3. We will run all of these test points for various scenerios. As a control, we will take the lights off of the tank and take ALL measurements in open air. Then we will test on tank at various hieghts from the waters surface (0-1 inch, 3 inch, 6 inch, or so).
4. Take & record all readings.
5. Make pretty graphs. (I've always love pretty graphs)

Other then this, I plan to retire from this thread, if at all possible. I do not wish to become caught up in mental masturbation, which is way too easy to do with lack of good scientific data (at LEAST on my part ).

Thank you all for your excellent thoughts and advice. We will have to see how this turns!!!

RE: Egg-grate/egg-crate/Lighting grid over aquaria

clsanchez77 — Thu, 02 Feb 2006 19:06:01 GMT

ok, I think I am starting to see somehting here, there is a difference between 'eggcrate' and a plastic/reflective diffuser. I assumed they were one in the same. I need to go back an reread this thread, after 12 hours of work today, all the information I read yesterday was overwritten.

Are the meters 'reasonable' for hobbyist to aquire (cost and access to purchase)? If not, where could I 'borrow' one.

I would like to try an experiment. I will be setting up tank new this month and would like to experiment with the eggcrate/diffuser issue. Also, my honeymoon will be the second week in May and we are going to Hawaii (very original, we came up with that idea ourselves) and will do plenty of snorkeling. I would like to see some readings there and compare to tank readings.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Thu, 02 Feb 2006 18:05:02 GMT

I suspect that Andy and Anthony are not far apart on this at all. Both, I suspect, would agree that you get more light if you use a good reflector and no egg-crate/louver. Both, I also suspect, would agree that it's generally not a good thing to have fish jumping out of your aquarium, so sometimes compromises have to be made.

There are "lensed" light diffusers that are much more efficient than egg-crate. I've often thought that acquiring one of those and drilling it with many holes would be a better option... but I haven't tried it, so I can't say for sure.

The thing I can say for sure, is that properly adjusted meters don't lie. So, like many things in this hobby, perhaps the best course of action is to test the effect for yourself. Then, you have all the information you really need.

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

clsanchez77 — Thu, 02 Feb 2006 17:23:02 GMT

Hey: I did not actually ask him about the eggcrate. I was questioning the my pendant mounting options and mentioned that the light would be flush with the bottom of the canopy top cover (about 5" from the top of tank, 6" from the water surface) and that I would have 2-VHO actinics and eggcrate.

His reply addressed my mounting options and then added a btw dont use the eggcrate as it restricts the light entering the aquarium.

My thoughts to this was 'back to the other board'. But what I wonder is that the eggcrate redirects the point source light downward, inhibiting its ability to diffuse for the entire surface area of the tank, or in other words, the far ends of my tank will be light deprived becase light that would normally 'scatter' to the ends of the tank is now directed by the eggcrate downward. A MS paint graphic would help here but I dont have time right now.

With flourescent, the light is already spread the full length of the tank by the nature of the flourescent light bulb, the eggcrate channels the light downward as dicussed here. So I wonder if the eggcrate interferes with the 'spread' of point source lighting if there is not enough space between the light source and the eggcrate for a meaningful amount of light to reach the entire aquarium surface.

Eggcrate is cheap, I will try it out and see what 'looks' best, but would be curious to see what you think. It is interesting that Andy and Anthony would go separate directions on a seemingly 'lesser' detail in this hobby.

Chris

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Thu, 02 Feb 2006 15:57:51 GMT

Mark... thank you for your input. The links are not presently working for me (I will try later).

And without dumbing down this discussion (and pending my peep at the linsk provided), i have to say that the charts and proprosition at large still beg the question that many people will ask: how is it that a diffuser grid whose intersecting partitions are a tiny fraction of an inch with a sum total of mere single digit(?) percentage of the surface area obstructed can block 50% of the light? It makes no sense. To then consider that this interface is not a flat one-dimensional obstruction, but rather an engineered louver that literally channels (more) light into the aquarium that other wise would have travelled "horizontally" (or some angle away form the target (aquarium inthis case) is just inconceivable. I'm thinking the charts above are wholly out of context for what we are discussing here.

What we are really talking about here is how much light makes it into the tank. It's about all that matters regarding best use of the resource (electricty in this case).

And for typical canopies mounted inches above the surface of the water without a light diffuser... light from the fixture strays. Turn all lights off in the room and you can see the light spilling out onto the floor in front of the aquarium, wall behind it, etc.

Then add the grid and see the stray light stopped. Channeled downward (yay!)

What has happend is that some light beaming from above is blocked by the grid. But more light that would have pass through the plane at an angel and never made it into the aquarium is channeled. There is a net gain.

And that is a better use of electricty. It is the crux of using a light grid to channel light. More of the light that we are paying to produce actually makes it into the aquarium.

That all said... there has to be some common sense emplyed here. Will the use of a light grid benefit everyone? No... of course not. I can envision a large aquarium (say 3' X 8') trying to reduce electric costs by have fewer but higher wattage MH lamps. Say... three 250 watt lamps instead of six 175 watters (one per 4 ft sq). For the employ of the former, there is considerable savings in electricty and lamp replacement. All for the compromise of strategically placing the zooxanthellate corals in the display under them. Now in this case... we do not want to channel much of the "horizontal" light downward. This is an example of needing spread versus intensity/focus.

Maybe that is what Andy is speaking to in the RC reference. It would not be a surprise since so many BB reef keepers are sps folks with exactly such setups... fewer bulbs of higher wattage.

But this thread here is not so specific. I do not believe we are only addressing huge tank owners or sps keepers with MHs bright enough to melt live rock.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Thu, 02 Feb 2006 15:28:22 GMT

I thought I was agreeing with you that one should believe the results of a light meter rather than a theoretical discussion.

And I didn't realize this constituted unwelcome mental masturbation. FWIW, one source of information about louver efficiencies is: http://www.energystar.gov/ia/business/Lighting.pdf which includes the following chart (small-cell parabolic louver is the item of interest):

Another, from one of the manufacturers is http://www.sdplastics.com/ALP/Para-Lite_4.pdf showing a louver efficiency of 53.3%.

Regardless, I think we can agree to dispense with the theoretical discussion and urge folks to trust their meters?

Best,

- Mark

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Thu, 02 Feb 2006 14:44:48 GMT

Mark.... I do enjoy constructive discussions. What I loathe is mental masturbation. I don't need a light meter to make me wonder how a discreet grid that comprises a fraction of the surface area could obstruct 50% of the light. And I do practice what I preach... this thread and my comments as stated in this thread detail that I did and do use my meter. If you don't want to take me at my word... do please just say so. I really don't enjoy sparring over the obvious or wasting time/post space on it.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Mark — Thu, 02 Feb 2006 14:32:23 GMT

Anthony Calfo (2/2/2006)

20-50%? How do you figure?

Can I add "but believe your meter to that?" I'll have to check some notes and see if I can find where I'm recalling those figures from. But, the intended point was to ask Andy why he made the recommendation.

RE: Egg-grate/egg-crate/Lighting grid over aquaria

Anthony Calfo — Thu, 02 Feb 2006 14:17:00 GMT

20-50%? How do you figure?