Reflectors
Contents:
- (F) Aluminum foil reflector idea - any problems?
by krogers-at-javelin.sim.es.com (K. Rogers) (25 Nov 91)
- (F) Aluminum foil reflector idea - any problems?
by ()
- (F) Aluminum foil reflector idea - any problems?
by ()
- Triton Enhancers
by Craig Bingman <cbingman-at-netcom.com> (Sat, 24 Aug 1996)
- saturation, reflectors, lamps
by Craig Bingman <cbingman-at-netcom.com> (Mon, 24 Feb 1997)
- Equation for Parabolic Reflector
by "Lam, Shing" <shlam-at-eee.hku.hk> (Sat, 01 Mar 1997)
- triton reflectors or the like
by George Booth <booth/hpmtlgb1.lvld.hp.com> (Thu, 04 Sep 1997)
- DIY reflector
by "Shimoda, Wade" <WShimoda/hei.com> (Tue, 6 Jan 1998)
- re: Reflectors
by "Christopher Coleman" <christopher.coleman/worldnet.att.net> (Wed, 3 Mar 1999)
- Reflectors
by The Eng Family <engfam/axion.net> (Wed, 03 Mar 1999)
- White paint
by MICHAEL SERPA <mserpa/bayweb.net> (Thu, 04 Mar 1999)
- DIY light reflector ideas
by bickford/black-hole.com (Jay Bickford) (Sun, 28 Feb 1999)
- White Paint
by Wright Huntley <huntley1/home.com> (Fri, 05 Mar 1999)
- White paint
by MICHAEL SERPA <mserpa/bayweb.net> (Thu, 04 Mar 1999)
- lighting reflectors (aqua mirror/AH supply)
by Michael Dubinovsky <mikluha/ix.netcom.com> (Tue, 26 Oct 1999)
- Reflector Material
by Gilbert Huard <ghuard/westsun.com> (Fri, 9 Jul 1999)
- Reflective inserts for flourescent strips
by busko/stsci.edu (Ivo Busko) (Mon, 25 Oct 1999)
- More Reflector Measurements
by busko/stsci.edu (Ivo Busko) (Fri, 18 Aug 2000)
- Reflector measurements (long)
by busko/stsci.edu (Ivo Busko) (Fri, 4 Aug 2000)
- Reflector measurements (long)
by "Wayne Jones" <waj/mnsi.net> (Fri, 4 Aug 2000)
- Reflector measurements (long)
by IDMiamiBob/aol.com (Sat, 5 Aug 2000)
- Reflector measurements
by Biplane10/aol.com (Sat, 5 Aug 2000)
- Reflector measurements
by busko/stsci.edu (Ivo Busko) (Mon, 7 Aug 2000)
- More reflector measurements
by busko/stsci.edu (Ivo Busko) (Mon, 14 Aug 2000)
- Dana Riddle Article - October FAMA
by "Roger S. Miller" <rgrmill/rt66.com> (Tue, 26 Sep 2000)
- (No Title)
by Wayne Jones (Tue, 26 Sep 2000)
- Lumens per liter
by Wright Huntley <huntley1/home.com> (Fri, 08 Dec 2000)
by krogers-at-javelin.sim.es.com (K. Rogers)
Date: 25 Nov 91
Newsgroup: rec.aquaria
jimh-at-ultra.com (Jim Hurley) writes:
>This idea is really quite poor. After I did it, it looked bad, so I removed
>it. Good thing I did, the varathane underneath was still wet and
>may have caused problems in the long run after I screwed in the
>canopy light holders.
>
>I'm trying to find an art supply place that sells reflective mylar.
>If anyone knows one, please tell me.
I used mirrored acryllic. It was 1/8" thick. For my hood the piece
cost me something like $6 (two years ago.) The price was well worth
it, IMO, as it was very easy to work with and is totally waterproof
and inert. I just glued the pieces into the hood.
--
Keith Rogers
Evans & Sutherland Computer Corp.
krogers-at-javelin.sim.es.com
by daveo-at-omews18.intel.com (David O'Brien)
In article <1991Nov25.214039.1070-at-ultra.com> jimh-at-ultra.com (Jim Hurley) writes:
>This idea is really quite poor. After I did it, it looked bad, so I removed
>it. Good thing I did, the varathane underneath was still wet and
>may have caused problems in the long run after I screwed in the
>canopy light holders.
>
>I'm trying to find an art supply place that sells reflective mylar.
>If anyone knows one, please tell me.
Go to your local hobby store that sells remote control plane parts.
One of the plastic wing coatings comes in a color called 'chrome.'
It's reflective mylar. The stuff comes with a heat activated glue on
the back side.
I used this stuff to coat the metal reflectors that came with a couple
of shop lights. A hair dryer was enough to glue the stuff to the
already painted surface. The glue also allows you to peel the sheet
back off if you want to. My sytem has been set up for more than a
year this way. Significant increase in light from the white painted
reflector.
--
Dave O'Brien (daveo-at-ichips.intel.com)
by richardb-at-cognos.UUCP (Richard Brosseau)
In article <1991Nov25.214039.1070-at-ultra.com> jimh-at-ultra.com (Jim Hurley) writes:
+This idea is really quite poor. After I did it, it looked bad, so I removed
+it. Good thing I did, the varathane underneath was still wet and
+may have caused problems in the long run after I screwed in the
+canopy light holders.
+
+I'm trying to find an art supply place that sells reflective mylar.
+If anyone knows one, please tell me.
Hydroponics stores will always have this in stock. Check your yellow
pages.
+--
+Jim Hurley --> jimh-at-ultra.com ...!ames!ultra!jimh (408) 922-0100
+Ultra Network Technologies / 101 Daggett Drive / San Jose CA 95134
by Craig Bingman <cbingman-at-netcom.com>
Date: Sat, 24 Aug 1996
> From: eis-at-alto1.altonet.com (Paul Nicholson)
> Merill Cohen said:
>
> >One thing that you both did not take into consideration is that "plain
> >old white" fades to yellow -- in both the paint and the plastic.
> >"Enhancers" remain the same -- only get dirty if you don't clean them!
> >When clean, they are like new. You would have to repaint the "plain
> >old reflectors"! (IMHO)
Paul said:
> I think that depends on the paint you use. How many white cars have you
> seen that have turned yellow? Applliances hold their color too. I've got
> some old shoplight fixtures that are still white.
Baked on enamel is a fairly UV resistant material. Most white paints are
not. I'm presently using a white two-part epoxy paint designed for
refinishing appliances and tubs, and it is holding up fairly well after 6
months of metal halide exposure.
White brush-on enamel exposed to light from metal halide lamps will
yellow in fairly short order.
Specular aluminum has one potential advantage/disadvantage over white
enamel or white appliance epoxy that has not yet been discussed: aluminum
has sustantially higher UV reflectivity than most paints. On paper, the
most UV reflective white paint would be white, high titanium dioxide
content acrylic, but the problem with acrylic is that it is water-based,
and not tremendously durable in a wet environment. Aluminum is reflective
into the far UV. There will be no blue/violet falloff as there will with
some white paints.
This is probably a bigger issue in a reef situation than in a planted
tank, but chl does have a fairly strong absorption feature at around 420
nm, and I'd like to hang onto that as much as possible. If there is any
yellowing in the paint, you will be losing reflectivity at the far end of
the visible/PAR region.
It isn't an effect that you will ever see with a lux meter, because of the
wavelength weighting scheme used for that unit. The weight goes to zero
at 400 nm, and is damned small at 420 nm.
Craig
by Craig Bingman <cbingman-at-netcom.com>
Date: Mon, 24 Feb 1997
About reflectors vs. white paint. I've done both, you can get good
results either way. I wish that it were as simple as mylar vs. specular
aluminum vs. powder coated stee vs. epoxy paint vs. acrylic paint.
It isn't.
There are a number of pendent metal halide fixtures around. They are all
white on the inside, and my guess is that the reflectivity of the
surfaces on the inside is all pretty much the same. Yet some of them
allow a lot more light to reach the aquarium than others. The shape of
the pendent is important, with some, there is excessive trapping of
radiation inside the bell. Tall skinny bells (Coralife) don't seem to
work nearly as well as more open bells (Iwasaki.)
So you can do better or worse even with white surfaces. When you get
into shaped specular reflectors, it gets hard really really fast. You can
focus light with them. That can be good, it can also be very bad.
For a bank of fluorescent lights as close to the surface of the water as
you can get them, I don't think white vs. specular makes much
difference. George has shown that before. Part of the issue is that you
pack the lights so tightly that there is a lot of trapping of radiation
on the back sides of the lamps, and it is immaterial what reflector is
behind the lamps when most of the photons emitted "up" just eventually
are absorbed by reflectors or lamps.
I'd like to see George repeat his experiment with four T-8 lamps spread
out over, oh, say 16" or so.
For metal halides that are 0.2-1.0 meters above the surface of the water,
it makes a lot of difference.
If anyone is truly hard-core about this, you can start running raytracing
simulations on your workstation. There are some interesting public
domain programs out there, and it turns out that even people who are
doing light fixture design professionally use this type of code to
simulate how well a given fixture/array of fixtures will work in a given
environment.
A friend of mine did some measurements with a spectroradiograph recently
on a number of metal halide lamps and halide fixtures. The hottest
ticket in the 150-175 watt class was the fixture being marketed by Two
Little Fishies. It has a professionally designed reflector, and does an
extremely good job of getting the light into the tank. It is also very
pretty. It is also expensive. ;-)
Another thing that people in the planted tank world might want to
consider is the spectrum of the various light sources they are using.
Not just from a "who drives photosynthesis best" perspective, but also
from a purely asethetic perspective. There are two main types of metal
halide lamps sold in the US. One, championed by Venture, is the Sc-Na
system. It produces very spikey spectra. The other is the so called
"dense line emitter" system. This produces a much better simulation of
sunlight. I've been amazed at how much better fish look under the
dense-line emitter type of lamp. This is much more of a CRI issue than
"color temperature" and on some level, I think the CRI numbers that I've
seen are somewhat less objective than the color temp numbers. Dense-line
emitter lamps are extremely nice. I'm in the process of redesigning my
light hood to let me use them. I've seen reef fish under both, and there
is no contest. Sc-Na system lamps just don't look as good as DLE lamps.
by "Lam, Shing" <shlam-at-eee.hku.hk>
Date: Sat, 01 Mar 1997
A good reference is
Author
Elmer, William B.
Title
The optical design of reflectors
Edition
3rd ed.
Imprint
Salem, MA : TLA Lighting Consultants, c1989
For normal aquarium hood with fluorescent tube, the
shape of the optimal cross section of the reflector
(so called small reflector) is somewhat like the "M"
logo of McDonalds.
Shing Lam
Hong Kong
by George Booth <booth/hpmtlgb1.lvld.hp.com>
Date: Thu, 04 Sep 1997
> Date: Wed, 03 Sep 1997 08:33:47 GMT
> From: mike-at-microspan.com (Mike Roberts)
>
> Does anyone have the measurements with the angles of the bends on the
> 'Triton Reflectors' that are meant for one fluorescent tube? Barring
> that does anyone have a good source of info for making DIY reflectors.
I have some but I don't think they are worth copying. You could
probably do better with a pencil and paper and some "ray tracing".
Draw your bulbs to scale and draw light rays coming from the center of
the tubes in all directions. Design the reflector such that the rays
reflect towards the water. Remember that light reflects at the same
angle that it hits the reflector but in the opposite direction. I
would think something in a W shape is better than the Triton's U
shape. Work on getting light out from behind and between the bulbs.
___ ___
/ \/ \
/ O O \
> 8ft tubes are hard to find reflectors for except for standard shop
> light fixtures and by my calculations I wouldn't be able to get enough
> tubes in my hood with that setup.
Have you considered 4' bulbs? You would have to buy more ballasts
initially, but might save money in the long run on cheaper bulbs and
you would definitely have a better selection of bulb types. 8' bulbs
are being phased out and may be harder to find in the future.
George
by "Shimoda, Wade" <WShimoda/hei.com>
Date: Tue, 6 Jan 1998
Hi,
Just to clarify things, my company, an electric utility, gives customers
a rebate for certain 'measures' that help to reduce their electric
consumption. One of these measures is the 'specular reflector', a piece
of metal with a mirror-like finish, specially formed to direct the light
downward (i.e., not just a flat sheet with a couple creases). Another
measure is the T-8 lamp (and accompanying electronic ballast). We have
no financial interest, whatsoever, in promoting one kind of measure over
another.
The first point I think I should mention:
The rule of thumb we use that Bob Dixon referred to, backed up by
measurements (which I used to have when working at another utility), is
that a four lamp fixture (plain white enameled box) can be 'gutted' and
retrofitted with a specular reflector and 3 lamps to give roughly the
same lumen output at the work surface.
Now for some confusion:
In an office, one of the main ways the reflector maintains the lumen
level is by redirecting stray light down to the work surface, light that
would otherwise be lighting the walls, etc. So, sitting at a desk under
the fixture, the report you're reading would look just as bright with
the reflector and 3 lamps, as it did with the original 4 lamps and white
fixture.
Previously I had assumed that the reflector would similarly help an
aquarium. From what I _now_ understand, without a reflector, some of
this stray light would reach the plants by being reflected off the
glass. So although I still suspect the reflector would provide more
lumens to the bottom of the tank, I don't know if the rule of thumb is
quite the same for an aquarium as it is for an office. My apologies to
Bob and anyone else to whom I previously wrote regarding reflectors. My
previous assumptions appear to be at least partially wrong. I am
familiar with reflectors, but unfortunately only as they apply to human
environments. I'm still learning about how they work in an aquarium.
The second point is in regards to the white paint vs. polished metal
discussion. I've heard a similar argument from a lighting consultant
about their 'reflectance' being almost the same, but haven't seen any
figures to back it up. Another thing to consider which you may have
observed is that white surfaces reflect light in a diffuse manner. That
is, the light striking the reflector at a given angle is reflected in
several directions. On the other hand, a mirror reflects light at an
angle directly related to the angle at which the light strikes the
mirror. That's why you can see yourself clearly in a mirror, but not on
a piece of white enameled metal. Any physics/optics experts out there
will hopefully clarify or correct what I just wrote. Some people also
believe that another reason reflectors can maintain lumen levels is that
rather than having the light bounce all around inside the fixture and
losing intensity before leaving the fixture, the mirrored surface sends
the light right out. As for me, I have sample pieces of specular
reflector material inside of my retrofitted hood.
Wade Shimoda
P.S. I'm not sure if this is what Matthew is referring to, but there
are ballasts with a higher 'ballast factor' that provide a higher lumen
level from a given fluorescent lamp, at the cost of greater electric
consumption. Ballast factors are applied directly to the lumen output
of the lamp, if I'm not mistaken. E.g., 3000 lumen lamp x 1.2 ballast
factor = 3600 lumens.
by "Christopher Coleman" <christopher.coleman/worldnet.att.net>
Date: Wed, 3 Mar 1999
> Olga Betts asked:
>
> BTW, I can't believe that white paint wouldn't be just
> as good as aluminum. Who out there knows the answer to
> that.
These figures are from an old hydroponics source. Unfortunately I
know longer have the URL. These figures, represent the percentange
of light reflected.
Mylar 90-95
Flat white paint 85-93
Semi-gloss white 75-80
Flat yellow 70-80
Aluminum foil 70-75
Note flat white paint is better than semi-gloss. Does this suggest
wrinkled tinfoil is better than non?
Hope this helps.
Christopher Coleman
christopher.coleman@worldnet.att.net
by The Eng Family <engfam/axion.net>
Date: Wed, 03 Mar 1999
>BTW, I can't believe that white paint wouldn't be just as good as aluminum.
>Who out there knows the answer to that.
>Olga
Hi Olga,
This exact same topic was discussed on one of my reef aquarium list a
couple months back. One person, Dana Riddle (www.aquaticwildlife.com), has
done many lighting studies on many types of light (MH, VHO and PC). He
found that a white surface did indeed reflect as well as the metal
reflectors. The only problem was that after sometime, 'painted' white
reflectors turned yellowish and were less affective. Someone on that list
is starting to use white rain gutters as a reflector and he will report to
the list if the white 'powder' coated metal 'yellows' over time.
Sincerely,
Victor Eng Vancouver, British Columbia, Canada
engfam@axionet.com
by MICHAEL SERPA <mserpa/bayweb.net>
Date: Thu, 04 Mar 1999
Victor wrote:
This exact same topic was discussed on one of my reef aquarium list a
couple months back. One person, Dana Riddle (www.aquaticwildlife.com),
has
done many lighting studies on many types of light (MH, VHO and PC). He
found that a white surface did indeed reflect as well as the metal
reflectors. The only problem was that after sometime, 'painted' white
reflectors turned yellowish and were less affective. Someone on that
list
is starting to use white rain gutters as a reflector and he will report
to
the list if the white 'powder' coated metal 'yellows' over time.
Being a grower of many different kinds of plants for most
of my life, I have tried just about everything under lites
at one time or another. I've probably read every publication
on the subject, in English, on growing plants under lites.
One common item,in these writings, has always been a list
on reflectivity values. And flat white paint has always been
near the top of the list. It's cheap, it's easy and when the
paint 'yellows' get out the paint brush! It ain't rocket
science and your plants will bearly know the difference. Your
wallet will!
Michael
- --
Michael Serpa * Bay Island Orchids
2311 Pacific Avenue * Alameda, CA 94501
Tel: (510) 521-8245 * Fax: (510) 865-1787
http://www.bayislandorchids.com
by bickford/black-hole.com (Jay Bickford)
Date: Sun, 28 Feb 1999
On Sat, 27 Feb., 1999, Chris Wells wrote:
>I'm in the middle of another DIY lighting project and I am looking for
>reflector ideas.
>I know you can buy nice reflectors through the mail but at ~ $40 for
two
>or three bulbs it just rubs me the wrong way. I will have a wood frame
>around the tank from which I will suspend the 6-8 T8 4' lights.
<snip>
Chris,
I bought a highly polished aluminum reflector for $18.00 from a
lighting contractor that specializes in retrofit lighting work here in
the Twin Cities area of Minnesota. I put it in an oak full hood on a 75
gal and fit three T-8's under it. If I had moved the bulbs a little
closer together, I could have fit four T-8's. The reflector was
originally designed to convert an older four bulb T-12 system to a
system that uses two T-8's, but still put out the same amount of usable
light.
I don't have any measurements with a light meter yet, but my guess is
the three T-8's with the reflector are as bright as most four lamp T-8
systems without a reflector or with a less efficient reflector.
I'm currently using Philips F32T8/TL950 lamps. (5,000 K color, 98 CRI,
and design lumens of 1860.) Philips has a similar lamp, the
F32T8/TL850, (5,000 K color, 86 CRI, 3050 design lumens) that is
brighter according to the specs, but has a lower CRI. I may try this
lamp the next time I buy some or set up another tank.
I think someone on this list said that the plants don't care a whole lot
about CRI, and I'm not sure if most people could tell a whole lot of
difference between 86 and 98 CRI anyway. I think the TL850 may be a
little less expensive than the TL950 as it is a little more common.
As this is the first time I have used this lamp (TL950), and this is a
new tank, I'll have to wait and see how the plants like it. So far, I
really like the way these bulbs make the tank look.
I hope this helps.
Regards,
Jay Bickford
Savage, MN
by Wright Huntley <huntley1/home.com>
Date: Fri, 05 Mar 1999
by MICHAEL SERPA <mserpa/bayweb.net>
Date: Thu, 04 Mar 1999
snip...
Being a grower of many different kinds of plants for most
of my life, I have tried just about everything under lites
at one time or another. I've probably read every publication
on the subject, in English, on growing plants under lites.
One common item,in these writings, has always been a list
on reflectivity values. And flat white paint has always been
near the top of the list. It's cheap, it's easy and when the
paint 'yellows' get out the paint brush! It ain't rocket
science and your plants will bearly know the difference. Your
wallet will!
Hearty agreement with Michael on this posting!
Having not been flamed, properly (recently), I can't resist adding a
comment or three.
The total reflectivity of a good white paint nearly equals that of
silver, and is certainly better than any aluminized surface (mylar,
foil or sheet metal). The difference between a diffuse (flat white or
brushed metal) reflector and a specular (polished metal or mirror)
reflector is the direction of the reflected light.
Over water, that just might have some effect, for light nearly
parallel to the water surface is reflected away, while 96% or so of
that incident nearly directly on the water does penetrate and go on
into the water.
Diffuse reflection scatters in all directions, so some of the light
must go back toward the tube or off at a shallow angle. Really
efficient specular designs (The McDonald's Golden Arches cross
section, for example) could, in theory, direct more of the light in
proper directions to go into the water better. Be sure and re-polish
them weekly, though. :-)
White paint has the huge advantage that the *shape* of the reflector
is totally non-critical, where shiny reflectors need careful
shape-control for any real efficiency advantage.
On plastic:
Unless specially coated, or otherwise treated to resist ultra-violet
light, the bonds cross linking plastic molecules are destroyed and
plastic will get brittle and fragile if exposed to strong UV light. I
have been using brown plastic rain-gutter material, with a brilliant
white interior, for at least 5 years with no obvious degradation. The
lights have usually been lower-level CW that put out little UV,
anyway, but the material was designed to take full sunlight and last
for many years. It works.
If you bought a plastic hood that is suspect, just line it with
aluminum foil and the problem will never appear. Replace the foil as
needed, and protect from spray.
That's my US$0.02 for this morning,
Wright
- --
Wright Huntley, Fremont CA, USA, 510 494-8679 huntley1 at home dot
com
One big difference between a Libertarian and a Demopublican is the
Libertarian knows it's not a waste to vote against a Republocrat.
http://www.self-gov.org/
by Michael Dubinovsky <mikluha/ix.netcom.com>
Date: Tue, 26 Oct 1999
>Date: Mon, 25 Oct 1999 13:45:45 -0400
>From: "Christopher Ferrell" <csferrel@nortelnetworks.com>
>Subject: RE: lighting reflectors (aqua mirror/AH supply)
>
>> ------------------------------
>>
>> Does anyone have experience using any products that are meant to increase
>> output of a flourescent? That Fish Place has Coralife/Energy Savers "Aqua
>> Mirror" polished anodized aluminum, which looks about the same angular
>> shape
>> as a flourescent strip. This shape, A H Supply claims on their web site
>> (http://www.ahsupply.com/36,40,or.htm) actually causes light to be
>> reflected
>> back onto the bulb (restrike). Of what use would better reflecting
>> material
>> be if it reflects back on the bulb?
Nope, it deosn't make any sense to reflect light back onto/into/on the bulb.
It just lost. Only UV light causes luminofor to produce visible light. If
visible photon hits luminofor it can only produce more-red, lower energy
photon (or even IR). If I remeber correctly this is Stocks law. That's why
no blue fluorescent paint exist.
In general, about 50-60% of light is lost when it hits the bulb. It only
causes bulb to heat and, therefore, its efficiency drops.
The one of the best reflector shape is similar McDonalds "M" where bulb is
placed near middle of "M". Light from bulb is reflected from mirror and
"goes around" the bulb.
>>
>> ------------------------------
>>
> I use 2 aqua mirrors over my 55 gallon tank. Each "mirror" has 2
>t-8s. I was running 3 t-8s in one mirror and upgraded to the 2 mirror/4
>bulb set-up just recently. I felt like the 2 bulbs/mirror would be more
>efficent than all four lights in a single mirror. The aqua mirror is made
yeap, one bulb in one mirro is relatively mor efficient than two bulbs. And
T5 bulb is more efficient than T8 (which better than T12)
>of two pieces of highly-polished aluminum that are screwed together in the
>middle. It can be adjusted from about 5" wide to about 12" wide (up to 4
>t-12s or 5 t-8s, albeit a very tight fit). Something to think about if you
>are planning on adding more lights (or taking some out) in the future.
>
> I just ordered a light set-up from ah supply. I can update everyone
>on how it works in a week or so. (comparison)
I ordered a lighting kit. Their price is very low comparing to other
aquarium suppleir. So far I got more light from 2 55W bulb than I had befor
from 120W total of fluorescent T12. At distance 10" (approx) my luxmeter
gave me around 2000 Fc (about 20000 Lx) before and 3800 Fc now. Of course,
it's not a true comparasing, because all T12 were Agro-Lite/Gro-Lux type
bulbs which have low lumen output (because they lack green light) and new
lights are 5400K. But, now I have plant bubbling after 20 min, insteead few
hours before. And plants grow like weed
SO far, I found two problems only:
1) my fishes are scared to death by new lamps. They don't swimm in open
space. I'm gonna buy something like hornwort to create more shadows
2) I see now all dirt/poop/etc that wasn't seen before.
Last one.
AH supply ballast doesn't have UL mark......so.....it doesn't comply to
safety standard (or they didn't get certification it yet). I'm gonna call
about this
Mike, who design weird optics around weird lamps
>
> What I really liked about both set-ups is that they are easy to
>install, they work well and they are fairly inexpensive for what you get.
>
> Chris
>
>------------------------------
by Gilbert Huard <ghuard/westsun.com>
Date: Fri, 9 Jul 1999
To: erik/thekrib.com
Hello again,
I'm just forwarding the link for the rosco products used for Light
control Material
referring to the last email I sent you.
<color><param>0000,0000,ffff</param>http://www.rosco.com/main.html
</color>
>Date: Fri, 09 Jul 1999 15:06:42 -0500
>To: erik@thekrib.com
>From: Gilbert Huard <<ghuard@westsun.com>
>Subject: Reflector Material
>
>I was reading a post by :
>krogers-at-javelin.sim.es.com (K. Rogers)
>Date: 25 Nov 91
>Newsgroup: rec.aquaria
>
>he was Asking "I'm trying to find an art supply place that sells
reflective mylar.
>>If anyone knows one, please tell me."
>
>This post is rather aged, But I do have the answer, I work at a Show
Lighting Production Company and we use a product manufactured by Rosco
called "Cinegel" in this swatch book there is at least 20 different types
of Mylar Reflectors they are either sold in 20" x 25' rolls or 20" x 24"
sheets for about $6.00 a sheet, as far as I know there is a Theatrical
supplier in every major city that would carry the Rosco Product Line, as
well, the glue (Roscobond) to apply it with.
>
>Best Regards
Gilbert Huard
Westsun Show Systems
by busko/stsci.edu (Ivo Busko)
Date: Mon, 25 Oct 1999
The AH Supply recommendation is correct. Flat-topped reflectors are way
less efficient than parabolic reflectors. You can judge a reflector by
looking into it from a distance when the bulb is installed (but with
the power off !). For an ideal reflector, you should see the bulb's
reflection covering all the available reflector surface. That means that
all the extra bulb surface that you see thru the reflection only is
actually delivering ligth into the correct direction.
To have a better idea, look at the pictures in
http://www.acropora.com/reefers2/main.asp?mscssid=
(go to their Metal Halide - Retrofit section)
I believe both the AH Supply reflectors and the Triton Enhnacer reflector
are designed in this way.
- -Ivo Busko
Baltimore, MD
by busko/stsci.edu (Ivo Busko)
Date: Fri, 18 Aug 2000
Biplane10@aol.com wrote:
> Ivo wrote:
>
> >Be aware that the Triton reflector is 6.5" wide, so it >won't fit in the
> >opening of your canopy. The AHS reflector is better in >this regard, it
> >is 4" wide.
>
> According to someone at A&H Supply, this reflector cannot be used with NO bulbs because they're designed for with with the PCF bulb, so they are not as wide at the top as would be needed.
>
> ??
>
> Sylvia
That's right, I didn't mean that AHS reflectors can be used with T12 bulbs.
If you have T12s and a narrow strip, you are probably stuck with less-than-
ideal reflectors, if any at all. No reflector can be efficient if there is
no space around the bulbs to redirect the ligth down into the water. This
is a problem common to all (that I know) low price aquarium hoods and strips.
- - Ivo Busko
Baltimore, MD
by busko/stsci.edu (Ivo Busko)
Date: Fri, 4 Aug 2000
OK, at last I got light measurements to compare different kinds of
reflectors for use in an aquarium fluorescent hood. Despite the
excellent material already available at the krib, in this archive, and
other sources, I wanted to see it by myself, since there are some
inconsistent results out there. I was particularly interested in seeing
if adding an expensive polished aluminum parabolic reflector would
be worth the cost of it, as compared with cheaper techniques such
as white paint or aluminum foil on a flat surface.
For the test I used my 20 gal aquarium hood, which is equipped with a
single 20 Watt T12 GE Plant & Aquarium bulb about 6 months old, driven
by a magnetic ballast. The hood was laid on a table (in a darkened room)
resting on its side, so the light points sidewise instead of down. At a
certain distance of the hood I hanged vertically a small piece of white
paper, aligned with and facing the center of the hood. This paper acted
as a diffuse target. I took readings of the target brightness using an
Olympus OM-2 SLR camera with a 200 mm lens. I also covered the entire
area around the target with a piece of black cloth to avoid reflections
from surrounding surfaces that could spoil the measurements.
I got readings at four different lamp-target distances, and using four
types of reflectors:
- - the hood is entirely made of black acrylic and its internal surface
is pretty rough, an almost perfect "black matte". So the hood by
itself, with just the light bulb in place, acted as the "no reflector"
reference.
- - lining the entire hood internally with white paper (regular A4 sheets
of Xerox paper) simulated a diffusive reflector. It can be argued
that white paint would make for a somewhat better reflector, and that's
probably true.
- - I also lined the hood with regular Reynolds aluminum foil wrap, shiny
side outwards. It is almost impossible to make a good specular reflector
out of this material, it gets wrinkled very easily. I attempted to lay
it out so the surface was as smooth as possible.
- - lastly, I used a Triton Enhancer reflector ($25), made of polished
aluminum sheet bent into a paraboloid shape.
So here are the results (in lux):
Distance No refl. White Alum. Triton
in inches paper foil
29 100 180 120 350
22 180 290 210 550
16 290 460 350 960
11 460 760 570 1560
A photographic photometer is not a very precise device. By repeating each
measurement several times, each one with a different focusing ring
adjustment and/or slightly changing the framing of the target, I estimated
that I can tell apart light levels that differ by 1/4 of f/stop. That
translates to about 18% precision, or equivalently a plus-or-minus error
of approximately +-10%.
Even with that modest precision, the differences among the different
reflectors are large enough to stand out clearly. There are a couple of
interesting effects that we can see if we plot the data as a function of
the inverse distance. If anyone is interested, e-mail me off-list.
The important point I want to emphasize here is the large gain provided by
the expensive reflector. It more than triples the light, as compared with
a no-reflector situation. A white diffusive reflector does provide a
more modest gain, of the order of 1.6-1.8, not bad if we consider its
cost (nothing). The aluminum foil reflector, on the other hand, is barely
worth the trouble. Aluminum foil would possibly make a good reflector only if
it can be laid out smoothly as a polished mirror. The wrinkles on the foil
turn it out effectively into a diffusive reflector, and a bad one...
This suggests me that the use of reflective flexible materials such as
Mylar and similar ones does not provide a significant gain above what one
can get with a simple white paint. They can be even worse than the white
reflector, as in my test. The reason is the difference between specular
and diffusive reflection. Unless the reflective material can be laid out
with a smoothness comparable with a true mirror, it will tend to act as
a diffusive reflector. And will most likely perform below the "perfect"
diffusive reflector, a white matte surface. Stretching this reasoning a
little, *any* shinyness in the reflective material is prone to *decrease*
the reflector effectiveness, unless it is *perfectly* smooth as a mirror.
That is, unless you can see your image clearly reflected when looking into
it.
An important point to consider though, is that with this particular
Triton reflector, probably the large gain only applies when the reflector
is used with a single tube. The dimensions of this reflector and its matched
lamp holders suggest that it is optically optimized to work with a single
T12 bulb. Nevertheless, the manufacturer claims that the reflector can
be used with two or even three tubes. With two tubes, the gain would not be
that impressive. The tubes cannot be placed precisely at the parabola focus
anymore, and that completely breaks down the reflector optical properties.
Also, the amount of self-shading and restrike gets large with two T12 tubes.
With three tubes, just forget it. The effect will probably be to *decrease*
the light as compared with a no-reflector situation, due to almost complete
self-shading and tube overheat.
Of course, these are "dry" measurements and in a real situation with water,
things can be quite different. However, my goal here wasn't to get absolute
values of light level at the inside of a water-filled tank, but to get a
*relative* comparison. Most likely, the relative performance of these
reflectors will still hold when used over a water-filled tank. I would
expect a slight decrease in performance of the diffusive reflectors as
compared with the Triton, due to large angle of incidence effects at the
water surface.
Btw, I cannot use the 20 gal aquarium to get these measurements, because
it is configured as a half-filled paludarium with lots of branching
driftwood and plants between the lamp and the water surface. I guess I'm
gonna need an extra 20 gal to continue this...
- -Ivo Busko
Baltimore, MD
by "Wayne Jones" <waj/mnsi.net>
Date: Fri, 4 Aug 2000
Ivo wrote:
This suggests me that the use of reflective flexible materials such as
Mylar and similar ones does not provide a significant gain above what one
can get with a simple white paint. They can be even worse than the white
reflector, as in my test. The reason is the difference between specular
and diffusive reflection. Unless the reflective material can be laid out
with a smoothness comparable with a true mirror, it will tend to act as
a diffusive reflector. And will most likely perform below the "perfect"
diffusive reflector, a white matte surface. Stretching this reasoning a
little, *any* shinyness in the reflective material is prone to *decrease*
the reflector effectiveness, unless it is *perfectly* smooth as a mirror.
That is, unless you can see your image clearly reflected when looking into
it.
I reply:
Mylar is a specular reflector. It is very cheap and can be easily bent
around a the inside of a shoplight reflector. If you don't glue it on and
just fasten it at the edges with that plastic extrusion stuff that is used
to bind papers together it naturally forms a parabolic shape. It won't span
a very great width though as it is pretty flimsy. By playing with the width
of the mylar you can get various suitable or less suitable curves. I
wouldn't lump it in with aluminum foil.
Wayne
by IDMiamiBob/aol.com
Date: Sat, 5 Aug 2000
Ivo's results are interesting and useful. However, he is
dismissing/discounting the reults with a "diffuse" reflector. The test was
set up with a "Target" to be hit by the reflector. If you are using a
pendant lighting system sitting a distance above the tank, this is the type
of information you want. If, like most of us, you have a strip light sitting
directly over the water, then a diffuse reflector is not so bad. Everything
that bounces off the reflector still enters the tank and most of it is
available to whatever plant can find a location within its path.
Now if Ivo were to repeat this experiment by measuring the light coming off a
piece of white paper underneath a tank full of water with the light sitting
directly on top of the tank, then he would have something more relevant.
Bob Dixon
by Biplane10/aol.com
Date: Sat, 5 Aug 2000
Ivo,
I appreciate your post but wanted to add a recent experience re: lighting and
reflectors.
I had 2 nearly new double strip Perfecto (white paint) reflectors lighting a
29 gallon tank. I was lamenting my green rotala macranda. My first step in
increasing lighting was to foil my two double strips. There was an immediate
change in coloring on the plant. In fact it turned red.
The white reflective part doesn't extend to the bottom of the strip, and I
reasoned the black portion might be wasting some of the light. I foiled the
whole thing, including the white reflector, for simplicity. So I really can't
conclude that the foil is superior to the white reflector, but it appears it
may be on these strips.
Sylvia
> The important point I want to emphasize here is the large gain provided by
> the expensive reflector. It more than triples the light, as compared with
> a no-reflector situation. A white diffusive reflector does provide a
> more modest gain, of the order of 1.6-1.8, not bad if we consider its
> cost (nothing). The aluminum foil reflector, on the other hand, is barely
> worth the trouble. Aluminum foil would possibly make a good reflector only
> if
> it can be laid out smoothly as a polished mirror. The wrinkles on the foil
> turn it out effectively into a diffusive reflector, and a bad one...
by busko/stsci.edu (Ivo Busko)
Date: Mon, 7 Aug 2000
Biplane10@aol.com wrote:
> Ivo,
>
> I appreciate your post but wanted to add a recent experience re: lighting and
> reflectors.
>
> I had 2 nearly new double strip Perfecto (white paint) reflectors lighting a
> 29 gallon tank. I was lamenting my green rotala macranda. My first step in
> increasing lighting was to foil my two double strips. There was an immediate
> change in coloring on the plant. In fact it turned red.
>
> The white reflective part doesn't extend to the bottom of the strip, and I
> reasoned the black portion might be wasting some of the light. I foiled the
> whole thing, including the white reflector, for simplicity. So I really can't
> conclude that the foil is superior to the white reflector, but it appears it
> may be on these strips.
>
> Sylvia
Sylvia, I believe the key here is the side of the reflector. I used to have
a double Perfecto strip and I know how the white reflector is. You can see
that the two bulbs are jammed close together and they effectively block a
substantial area of the back reflector. The back area of the reflector
is not doing really much. The sides are the areas responsible for most of
the reflection. If you add anything reflective there, the overall performance
is bound to improve, as you noticed. However, my measurements where conducted
with a large flat reflector behind the bulb. I don't know if they can be
extrapolated to your situation, where most of the reflection comes from
slanted reflecting surfaces at the sides of the bulbs.
- - Ivo Busko
Baltimore, MD
by busko/stsci.edu (Ivo Busko)
Date: Mon, 14 Aug 2000
A few days ago I posted some measurements that compare different types
of reflectors
(http://www.actwin.com/fish/aquatic-plants/month.200008/msg00069.html)
These measurements where made "in air". Then I got hold of a spare 20
gallon tank that enabled me to re-do the measurements under actual, or
almost, conditions found in aquaria. This test aquarium was kept bare.
It has a black acrylic bottom pane where I put a white china saucer to
act as a diffusive target. The aquarium was filled to the top, which
resulted in a depth of 13" between the target and the water surface.
The same hood I used before was lined with the same materials, top,
front and back internally. The hood was put on top of the aquarium such
that the distance between the light bulb and the water surface was 1"3/4.
Measurements were taken in the same way as before, using my SLR camera.
Here are the measured illuminances, in lux:
no reflector: 500
white paper: 910
aluminum foil: 840
Triton Enhancer: 1680
So again we see the same behavior as before, somewhat altered by the
effects of total internal reflection inside the tank. All four measurements
are significantly brighter than their in-air counterparts, even at a
14"3/4 target-bulb distance, as opposed to the minimum 11" distance used
for the in-air measurements. So we may conclude that internal reflection
_does_ take place, and it _is_ an important effect. However, the tank was
clean and bare, and in real tanks the effects of plants and dirty glass may
subdue internal reflection effects in way that might be very difficult to
quantify.
The gain factors provided by the different reflectors when compared with
the no-reflector (or black reflector if you wish) case are similar in
the in-air and in-water cases, given the measurement precision. The only
one that is a bit off is the aluminum foil reflector. However, this could
be explained by the fact it is almost impossible to build consistent
reflectors out of this material. Even small unavoidable wrinkles seem to
lead to very different reflecting properties.
Anyway, the fact that in-air and in-water measurements show the same
relative gain factors for the tested reflectors suggests that any
"optical coupling" effect that might exist between the light fixture and
the water-filled tank, and which would favor diffusive reflectors, is
minimal. In other words, specular reflectors that are able to redirect
most of the light into a parallel beam perpendicular to the water surface,
offer a large gain over reflectors that spread the light over all directions,
such as diffusive reflectors, even when these are kept close to the water
surface. I would even dare to suggest that specular but plane reflectors
do not offer a significant improvement over diffusive ones, just because
they do not form a parallel reflected beam, but reflect light in a pattern
similar to the pattern of reflection created by a Lambertian diffusive
reflector.
The problem I find with those parabolic mirrors is that they only work
well with a single bulb. Move the bulb a little off from the focus
position, and the reflected beam completely breaks down. It remains to be
seen by how much the performance of one of these reflectors degrades with
say two tubes. More measurements on the way, I' afraid...
- -Ivo Busko
Baltimore, MD
by "Roger S. Miller" <rgrmill/rt66.com>
Date: Tue, 26 Sep 2000
On Tue, 26 Sep 2000, Victor Eng wrote:
> I just read the Dana Riddle article on how Eggcrate can increase the
> lighting in a tank by 25%. Apperently the eggcrate has a thin side &
> a thick side. If you put the [thick] side facing up this causes the increased
> light effect. Mr. Riddle uses a 400w MH but it has to be placed 3-4 inches
> above the eggcrate. Anyone have any experience with this or have any
> thoughts?
I can't figure out any mechanism that would allow lighting egg crate to
increase light intensity compared to an open-top tank with the same
lighting.
I've been using lighting egg crate as tank covers on fluorescent-lit tanks
for several years. The egg crate I use doesn't fit Dana Riddle's
description; it's white with 1/2 inch squares and the plastic is the same
thickness everywhere. Compared to a completely open-top tank, the egg
crate may reduce the lighting a little, but not a lot. Compared to a
glass top (or at least my former dusty, encrusted glass tops) the egg
crate is a big improvement.
Charley Bay reports elsewhere in this digest that evaporation rates with
egg crate covers are as high as in open-top tanks. I don't find that to
be true in my tanks; for me the evaporation rate in tanks covered with egg
crate is between the rates I get with glass covers and the rate I get with
no cover. My light fixtures cover all but a few inches of the top of my
tanks and that may explain the difference between Charley's observations
and mine. My tanks are covered by the light fixtures, with or without the
egg crate.
Increased evaporation lets my egg crate-covered tanks run cooler in the
summer than they did with glass covers. On the down side, I think it was
Dave Wittaker who pointed out once that jumping fish can injure themselves
on the edges of the egg crate.
Roger Miller
by Wayne Jones
Date: Tue, 26 Sep 2000
> >
> >...It has an amazing effect when it is placed under the
> >fixture. If you stand to the side and look at the fixture you
> >can barely tell if it is even on. For some reason they are
> >is referred to as parabolic grills...
> >
> >It wouldn't suprise me at all if that they increase the light
> >entering the tank. They restrict the angle of the light hitting
> >the water surface so more light enters the water...
A couple of years ago the local Food Lion upgraded their lighting from
4-foot T12s to 8-foot T8s, even within their office space. The old fixtures
from the offices had these gratings, which I originally talked them out of
for use in supporting rocks and stones, keeping "diggers" from reaching the
fertilized portions of the substrate, etc.
When they told me they were available for pick- up, I was disappointed to
discover that they were coated with an aluminized Mylar- type finish. Being
wary of this finish in a substrate, I decided instead to fit them back into
some lighting fixtures. I was amazed at the difference - almost all of the
light leaving the grate falls *straight down* - no discernable diffusion at
all and a very tight illumination pattern at tank distances.
Unfortunately, I eventually discarded them anyway - these particular grates
were pretty well "weathered" and beaten. The "aluminum" started flaking away
with handling, which I *didn't* like at all since it tended to end up in the
tanks.
Not to worry, though. These grates were the originals from the store opening
over ten years previous. I don't imagine fresh ones, properly cared for,
would be problematic...
- -Y-
David A. Youngker
nestor10@mindspring.com
by Wright Huntley <huntley1/home.com>
Date: Fri, 08 Dec 2000
> Date: Fri, 8 Dec 2000 13:18:44 -0500
> From: "Daphne Freeman" <daphne.freeman@home.com>
> Subject: Lumens per liter
>
> Wright mentioned AH Supply's reflectors and 3M's Silverlux silver. Familiar
> with former but not latter. Is that another PC reflector or just a coating
> or what? Never heard of it. Know AH's are supposed to be great and the
> Spider Light is supposed to be great for MH. Shopping for MH reflectors and
> it sounded interesting... Thanks.
It's a flexible, silvered Mylar thing that can be glued inside any hood, but
would work best in a properly-shaped reflector. The 3M web site describes it
and its fairly-worthless aluminum twin, also called "Silverlux." It is self
adhesive, by peeling off one side, and protected until installed, like the
AH reflectors, with a peelable cover on the working reflector side.
I'm playing with using some for 4' T-8 tubes. [The AH reflector is designed
for CFs.] I hope to stick it to flat aluminum, and then bend it to the
desired "golden arches" shape that gives best efficiency for a small, round
tube. There's a picture on their web page of a man installing exactly what I
want, but so far have not found either a shop willing to do them for a
decent price, nor the maker of the "troffer" they show.
See http://www.3m.com/market/construction/html/products/product193_p.html
One small problem. I think minimum order from 3M approaches $1500, and would
be more than enough to equip all the serious US planted aquaria! :-)
Wright
- --
Wright Huntley, Fremont CA, USA, 510 612-1467
"Government, in its very essence, is opposed to all increase in
knowledge. Its tendency is always towards permanence and against
change...[T]he progress of humanity, far from being the result of
government, has been made entirely without its aid and in the face if its
constant and bitter opposition."
-- H.L. Mencken
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