2'x7' SHEET POLISHED ALUMINUM

[suthrnmn]

anyone know where to find some material for a MH reflector. thanks.

[douggiestyle]

read this thread

http://www.reefcentral.com/forums/showthread.php?s=&threadid=995617

[mistermikev]

haven't used it yet but a mud troff for drywallers would work excellent. stainless steel, 22.5 degree angles, 12 or 14inch for $10! Saw it at home depot. It is polished to a mirror finish. Just have to create a hole in one side for the fixture. hope this helps!

[suthrnmn]

found some marine grade mirror polished 2x2 sheets for about 32 bucks each here under the suppliers header. sorry cant paste it here. and thanks for your response. still looking.

[BeanAnimal]

Before you spend the time and cash on the materials and reflector you need to outline your goals and come to terms with the limitations of a DIY MH reflector.

There is a lot of misconception and misinformation floating around regarding what makes a "good" reflector. Some will tell to use materials such as "white paint" or "specular aluminum" or "tinfoil" or "mylar". Othere folks will recomend "a parabola" or a "batwing" or a "hexagonal box" type of shape.

The reality of the matter is much more complex. A reflector has a sole purpose.... That is, to take the light emitted by a tubular shaped lamp and bounce it into the desired focus area with a FEW surface interactions as possible.

Every time a "ray" of light strikes an object, that light is reflect away at the same angle that it strikes the object. The ideal reflector would take each ray of light and with a single bounce, direct that ray of light to the waters surface, at an angle greater than the critical angle of reflection (we want to pentrate the water, not bounce off!!). Herein lighs the problem. There is no perfect shape that will achieave this. The bulb creates it's own shadow and blocks some of the light and some of the light strikign the water will bounce off because the angle is not steep enough. Then we have to worry about the focus and the light that is not making it into the water. So we make some compromises based on the bulb diamter and desired focus of the light. Some of the light strikes the water on once bounce, some two or three or more bounces in the reflecor.

What this means is that a great reflector is a highly engineered shape.

Thats not all...

No surface is perfect. If you look at the aluminum (or any surface) under a microscope, you will find it to be covered with little mountains and valleys. These are all at different angles. When the light strikes the aluminum, these little peaks and valleys send the light scattering in all directions. This scattered light, instead of going where intended jets off in unwanted directions. Some of it striking other parts of the reflector, some missing the water and the reflector all together. Of the light that hits the reflector, it is scatttered once again... and again .... etc. This means that the surface needs to be as perfect as possible or parastic losses will quickly add up. The same concept applies to man made imperfections. Every slight dent, scratch tiny bending error and imperfection add up to an overall loss of efficiency compared to a "perfect" reflector.

Other problems like hotspots and dulling of many of the readily available DIY materials make this a daunting tasks.

So there was the explanation... what is the reality?

Well a LOT of the reflectors out there are garbage when it comes to shape. Some of that garbage does incorporate decent reflective material and fairly precise bends. There are a few designs that are fairly sophisticated.

Your DIY reflector, if done perfectly will likely not be any better than the cheapy commercial units and likely cost a LOT more to source and fabricate. They simply have no chance of being better than some of the good designs out there.

There are just simply too many things working against you that you have no real chance of overcoming if your goal is to build a better reflector or save money. From talking with others and looking at the differences in commercial designs at sanjays website, it is easy to conjecture that any well done DIY design will be easily 50% less efficient than the better of the commercial designs. That means less light in your tank and the need for higher wattage bulbs or more lamps to make up the difference.

On the other hand if you goal is just good old DIY fun and satisfaction, then you are on the right track :)

You may have some success DIYing a lumenarc type reflector... others seem to have had decent luck in that arena. But once again your bends will have to be pretty damn accurate and your choice of materials is limited. You can buy the lumenarcs for less than $100 or so at police auction sites and new aquarium style units for $149.

[RV8tor]

Well I hope this helps, the best place to look is a aircraft supply, I know that you are not into tensile strength and and PSI but this is where I get my stock aluminum from and if you are into polishing you can use a good automotive polish or I particularly like the nuvite product, but I have to polish bigger areas on my other hobby. I would get the thinest sheet .016 or .012 I think is the thinnest. I use this place and they will cut the sheets for you if you ask. The aluminum has a plastic sheet over the shiney side but it is not REAL shiney it is ALCLAD aluminum, I had my DIY reflectors on for over a year and are a shiney as the day I made them.

[http://www.wicksaircraft.com/catalog/product_cat.php/subid=5702/index.html

http://www.nuvitechemical.com/

good luck

[BeanAnimal]

hows the plane these days?

[fio1022]

Anyone ever try pieces of mirror?

[douggiestyle]

mirror not good. the light must pass through glass then hit reflective surface and then back through glass. now keep in mind that the light will be bouncing around in there a bit. so in essence half the light could pass through 1/2" of glass (more or less) before it ever reaches the tank.

[MinibowMatt]

Bean, Im not one to disagree with you on the science behind a reflector, but for many people DIY is a first choice because it is fun and cheap. If we were homebuilding lasers than I can see where the light bounce has to be perfect. But the fact is, most of us upsize our lighting for a tank, and that upsize will compensate for individual light rays lost due to excessive bounce. Ideally your statement is 110% correct. But our DIY stuff isnt meant to be ideal, its meant to serve a purpose. I have read your thought on reflectors before, and it seems to me you really dont want people to DIY their own reflectors?
Personally, when money is tight(or intrinsic drive is high) I will DIY -- regardless of what anyone here would tell me, and on that premise, offering the OP tips on how to make the best reflector would be more helpful in this situation.

[BeanAnimal]

For"fun and cheap" are very valid reasons to build a reflector. Yes many of us upsize or lighting, or our corals could do with "less" anyway. Using that thinking as a parameter, then the losses of a DIY reflector do not matter. On the other hand, thread after thread is about maximizing our lighting and with that as a parameter a DIY reflector makes no sense at all becuase of the losses.

When we DIY things, we try to build better than we can afford. At least that is the goal most of the time. Skimmers, sumps, maxi streams, etc.
There are some things that we DIY because we can do it better no matter what the cost, controllers and maybe high end skimmers would be a good example.
Very few DIYers set out to build something inferior, let alone something that is realativly cheap to begin with. When we do set out on project like this, we usually do it in the "fun and cheap" manner (as you already mentioned).

My intent is not to prevent people from building DIY reflectors. My intent is to ensure that their expectations are grounded in the reality of the situation.

Lets draw a parallel.
You can DIY a dragster engine, but you certainly will not be casting your own cylinder heads and engine blocks. You "could" but the cost involved and the final product achieved will not be competative.

After reading the reviews and looking at Sanjays data, it is very obvious that a DIY reflector will simply not perform. There are just as many people running around saying that "white paint" or "tinfoil" are good choices. Most look at these things as simple devices that are no different than coffee mugs or overflow boxes and in then come to the conclusion that anything "close" will work close enough.

As far as tips... I think my post offers a lot of good information. I am not sure how to make the "best" diy reflector because I do not have the tools to calculate or bend one. I suppose the "best" thing to do would be exactly copy a well designed commercial unit. Anything else is a shot in the dark.

I aplaud those who want to DIY anything and even ignore the advice and plaud onwards. Afterall part of the DIY spirit is ignoring the naysayers anyway.

[douggiestyle]

i aggree with whats been said about diying a reflector. i must say though that it all depends on your desired end result.

1. before you buy a reflector, do some research. just because its expensive and "looks" engineered does not mean that it is

2. what are your goals. if you have a white painted diy hood and you have some polished aluminum or access to some inexpensive reflective goods. yeah lining the hood with it would be better than the paint.

3. if you do some research you will find that parabolic trough designs are the most common used in horticulture as well as other lighting. it is also very easy to do, and very efficient. so again do some research, and maybe use a paradolic design. no sense in reinventing the wheel.

[suthrnmn]

wow, thanks for a great response. when i put together my 120 my retro fit reflector was simply a flat piece of polished aluminum. i ran 4X250X20k mh s on this tank now for i guess 5 yrs+- and have had great success with high light demand sps. now im working on a 265 84X24X30 and wanted to basically duplicate what i had, but, what you say makes a lot of sense regarding "lost light". so in your opinion, who makes the best reflector that i can add my sockets etc. that i already have. my intent is to run 6X250X20k on this tank, plus some vho actinic.

[BeanAnimal]

Sadly much of the commercial stuff is pure garbage with NO engineering. The older SE stuff was certainly like that. Things have started to change with the DE HQI stuff and T5s.

I honestly do not pay much attention to the SE reflectors... if you still want to DIY them you do want to look into the luminarc style DIY stuff... kentrob and some others here have done a good job mimicing those designs.

SLS has some smaller reflectors that are the same basic shape... check their website (lumenmax I think). You may want to check sanjay joshi's website for the skinny on some of the SE reflectors he has tested as well. Here is his home page with links from there... http://www.personal.psu.edu/faculty/s/b/sbj4/aquarium/aquarium.html

Bean

[MinibowMatt]

Thanx Bean for your thoughts. I wasnt trying to "get you" as I respect your knowledge as a DIY'r .

I do feel (from experience) that a very good reflector can be had by some simple bending of a specular aluminum. If a DIY'R was to research a good Parabolic Reflector, and copy that design, you will be building one plenty better than most commercially available ones.

[RV8tor]

<a href=showthread.php?s=&postid=8807651#post8807651 target=_blank>Originally posted</a> by BeanAnimal

When we DIY things, we try to build better than we can afford. At least that is the goal most of the time.


Plane is doing great thanks for asking Bean, but it is time to repolish it for the spring. Oh BTW this was also a DIY because I knew I couldn't afford to buy one so I built it. Anyways I love DIYs. But one must also to research too.

[BeanAnimal]

Ohh no problem at all... I did not take your post any other way :)

The problem with the straight parabolic is the bulbs shadow... but yes with a bit of effort you could DIY something close to the unrefined designs. Material choice becomes a slight problem, even some of the junk uses some decent material.

I have heard decent reports about the sola tube material. You can also buy reflective sheet that will outperform the specular stuff and associated hotspots and delicate surface.

Somebody with a par or quantum meter could tinker with a few DIYable designs and come up with something useable for average bulb sizes...

I like my ROIII simply because they were somewhat inexpensive esp if you take the DIY cost into account.

I am all for DIY reflectors for T12 and PC bulbs as there are very few good units out there. I also think lining the inside of the hood with a parabolic or at least curved reflector is a good idea. Some of the light that bounces off the water will find it's way back.

[BeanAnimal]

Did you really end up saving money on the plane? My "big" technical DIY projects usually end up going 5x over budget when I add ALL the stuff up (the nuts bolts and dodads that I neglected to budget in, mistakes, extra trips to the hardware store, tools you found out you had to have, broken tools,... you know the stuff you never tell the wife about when she asks how much it has cost so far!)

[douggiestyle]

thanks for the link to sanjays site.

the plus you have suthrnmn. you all ready own the stuff. by adding in some good reflectors (diy or store bought) you may be able to use your existing system and light the larger space with out purchasing any additional lighting equipment.

[jman77]

Use Extension Kits for Tubular Skylights from Home Depot or Lowes.
Don't listen to people that say you will not save money on DIY reflector ...because you can easily , or that it will not works as well as the one's you buy premade.

[BeanAnimal]

jman77 with all due respect...

If you read the information above, you will see why and how they may or may not perform as compared to "premade" units.

In some cases it may be possible to build a reflector that outperforms a mediocre commercial unit. In most cases with most people skillsets, tools, and knowledge, the task is an uphill battle. Building a unit that outperforms the well designed units will be nearly impossible for the average DIYer.

Asking somebody to "not listen" without adding any supporting evidence is asking them to ignore reality or the provided the information provided by those who have a technical grasp of the subject. If that is your opinion, then you are more than welcome to have it... but it flies against the hard facts surrounding reflectors and how they work. Is there a quantifiable reason that you feel a DIY unit can be cheaper and beter than a good store bought unit? Or is it just pesonal opinion? If it is just your opinion, then I (or anybody here) will not likely change it, but that is not the goal anyway :)

Also, the "sola tube" product listed above IS a skylight kit/extension and was recomended by myself and others :)

[BeanAnimal]

FWIW efficient reflector design should yield a unit that puts 90% of the light in the desired focus area.

For more than you EVER wanted to know
http://hep.uchicago.edu/solar/light.html
Notice the "batwing" or "spider" shape that is formed by the parabola with a peak in the middle.... The hexagonal or sqaure units are a simple compromise that is easy to scale shape and bend (straight bends instead of complex curves). From everything I have read, the best "box" type reflectors are only 80% efficient with tubular bulbs. The better "batwing" designs are not open ended (a place for a significant amount of light to escape)

The complicated part is actually forming a parabola and not a constant curve... errors COUNT bigtime. The complicated part is getting the parabola sized to fit the given bulb and getting the peak correct, again errors COUNT.

This is why a die stamped unit may achieve 90% efficiency for the desired footprint... and the DIY shaped copy only 60% efficiency.

This same science and theory is used with radio, solar, laser and other fields where reflections of propogated waves are dealt with and shaped.

It is nice to see that at least some of the OEMs in this hobby are starting to take the time and money to actually engineer shapes instead of just "DIYing" them.

[douggiestyle]

that bat wing design is very similar to a few t5 reflectors ive seen.
but it is very dissimilar to most all halide reflectors.

[grouper therapy]

try http://www.awood.net/ they have polished aluminum 4'x8' sheet for $97.00 they have a n.c. location

[douggiestyle]

i love this.

"ISN'T THIS AN UNGODLY MESS TO WORK WITH? DON'T WORRY WE SIMPLIFY IT LATER!"

[BeanAnimal]

So you really are reading it.... visions of doing DIY REAL reflector design?

http://cycloptics.com/fauto2/fauto2.html
http://cycloptics.com/programs.html

They can design whatever you want... it is what they do! Not so sure about the capabilities of their software...

The "inustry standard" reflector and optics packages are CODE-V, ZEMAX and FRED. Others that fit into that market segment are ASAP, Trace Pro, OSLO.

Likely not available without a bank loan and certainly not popular enough for the warez monkeys to hack. So that leaves us with websites similar to those linked to above.

Like I said... efficient reflector design is highly comples. It is one thing to bounce light around, another to drop it on a focused area. How many of the commercially available hobby units are highly efficient.... that I do not know.

[billy72]

Bean,

Are there any light manufactures using this 'batwing' design for their linear fixtures?


Its nice to see the math behind it understand in my younger days.

Certainly appears to be the most logical shape. Anybody use that shape in their DIY's

[douggiestyle]

<a href=showthread.php?s=&postid=8810265#post8810265 target=_blank>Originally posted</a> by BeanAnimal

Like I said... efficient reflector design is highly comples. It is one thing to bounce light around, another to drop it on a focused area. How many of the commercially available hobby units are highly efficient.... that I do not know.

my view is the same, with a big stress on the 2nd part.

:smokin: my daughter wanted this here.

so anyways. i think about how people have those hamiton reflectors or those diy kits that come with a 12x12 piece of flashing. and thats my main point about diying a reflector.

now lets take this to another level. no speak on warez. thats illeagle. now, i know a guy who knows this guy who knows this guys uncle.............

im sure a few of us have those connections?

[douggiestyle]

<a href=showthread.php?s=&postid=8810526#post8810526 target=_blank>Originally posted</a> by billy72
Bean,

Are there any light manufactures using this 'batwing' design for their linear fixtures?


Its nice to see the math behind it understand in my younger days.

Certainly appears to be the most logical shape. Anybody use that shape in their DIY's

spider reflectors

[BeanAnimal]

had to quote me, spelling disfunction and all... geeze


Yeah I shoulda never used that word... my point was that the software is so scarce and specialized that not even the hackers bother to exploit it.

I don't think the spiders fare two well in real world testing... They lack end reflectors which causes a HUGE performance hit. They are also lack focus. If you read the tech article I linked to, and then compare that to a "box" type reflector or one with FACETS.... you will find that the box and faceted reflectors crate a sharp focus edge as opposed to a soft one.

So... the parabola may be more efficient at getting light from the bulb moving away from the reflector, but the boxed or faceted reflectors are more efficient at getting that light into the focus area without spillover.

I think you will find that the ROIII and similar reflectors are FACETED PARABOLIC shapes. A long time back somebody argued tha that the facets were just a cheap way of making a parabola... in reality it is a way to focus the light in desired area and create a harder terminator.

anyway here is a very good link that does a much better job of explaining some of the basics ... of course it is Sanjay once again.

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

take note of the distances and footprints... see HOW MUCH focus area makes a difference as to where the best mounting height is. remember distance kills here because of the inverse square law. However some shapes require distance to get spread.... ahhh starting to get even more complex!

In theory every mounting height and tank dimension (desired focus) would have an optimum reflector shape for a best operating point :) But the size and shape of the bulb are a big part of the optimization....

I think you will find some of the newer units come with focus parameters for different mounting heights.

[suthrnmn]

i would like to take this opportunity to thank you all, i could have never earned my phd in aqua light diy reflectology with out you!!
merry Christmas.

[RV8tor]

<a href=showthread.php?s=&postid=8808659#post8808659 target=_blank>Originally posted</a> by BeanAnimal
Did you really end up saving money on the plane? My "big" technical DIY projects usually end up going 5x over budget when I add ALL the stuff up (the nuts bolts and dodads that I neglected to budget in, mistakes, extra trips to the hardware store, tools you found out you had to have, broken tools,... you know the stuff you never tell the wife about when she asks how much it has cost so far!)

No I saved about 1/2 of what it is worth but it is going up every year. You get it in a kit but you have to by the engine, paint, interior, prop and instruments, still cheaper than most speed boats.