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Best material & shape for a reflector


Mr. Fosi

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Since I got the new fixture in, I have been thinking of ways to maximize the output of my 2x65W bulbs. The way I see it, if the reflectors are crap I could be losing up to 50% of the emitted light.

 

Some things I have read suggest that a flat white reflector retains the most spectral quality while others say that polished metal is the best.

 

All fixtures that I have seen have used some form of polished steel or aluminum, but I have never seen the inside of a more expensive fixture like an orbit.

 

Parabolics seem more expensive, does that mean they reflect more light?

 

Does anyone have any links or expertise in the area of optics and reflected light?

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SplitSequence

speaking from a purely optics perspective, the parabolics are REALLY the way to go, you lose a lot of wattage to having a flat reflector for no good reason.

 

As for the material, if i had to have a hunch about it, i would lean towards the polished metal, but only because that's all i've ever seen. It doesn't seem like white would reflect as much, at least in the visible spectrum.

 

~Chris

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... you lose a lot of wattage to having a flat reflector for no good reason... It doesn't seem like white would reflect as much, at least in the visible spectrum.

 

Yeah, that is the same way I was thinking, but I don't really have anything solid to back it up. I am kicking myself now because I never bought the books for my physics classes, so I have no pertinent reference material on my shelves.

 

It would probably be next to impossible to make your own parabolic reflector, but I'd hate to buy one... I have visions of tinfoil stapled to cardboard. B)

 

Still hoping for a couple links or solid references.

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SplitSequence

As for the credentials, would a doctorate student in mathematics be solid enough for you?

 

Most places don't actually issue a true parabolic, but rather an approximation by bent, angular pieces of metal, so cardboard and tinfoil would work.... in theory...

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As for the credentials, would a doctorate student in mathematics be solid enough for you?

 

Sure, but I didn't mean personal references (soon-to-be biology doctorate student here). I was speaking of articles or links, like this one:

 

http://www.falstad.com/ripple/ex-parabola.html

 

... cardboard and tinfoil would work.... in theory...

 

But not necessarily in practice, plus it would look fugly and be a pretty good insulator inside a closed fixture.

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SplitSequence

Rock on. As for the theory/practice part, that's not really my territory. ^_^

 

I can't really offer you more than hunches and what would probably seem to be abstract nonsense in this case, but i do think that your intuition has put you on the right track.

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www.ahsupply.com has the best, most effective reflectors available for PC tubes. There are available individually but you may need to call or email if they are not listed individually. Honestly, Kim at Ah is a great guy to deal with.

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www.ahsupply.com...

 

Thank you for the link. I have perused AHSupply before, but I had forgotten about them.

 

The only bummer is that I could find no pictures of reflectors on the site, so I emailed Kim and asked if she could email some to me. If she does, I'll post them here.

 

Any other good links or resources out there?

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Hi,

 

Look at the top and middle of the 36-55watt Kits page (http://www.ahsupply.com/36-55w.htm ) and the top of the 96w Kits page.

 

Regards,

A H Supply

 

The pics were easy to find once I was pointed in the right direction.

 

I really like the way those reflectors look, but I can't spend $37 for two of them, so it looks like I'll be using the crap reflector for a while.

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reefman23

I copied the angles from the ahsupply.com reflectors and made my own. They work very well...

 

t_finishing_canopy__3_1711.jpg

 

IMGP1421.jpg

 

That MH reflector was made by me too. Used simple drawings with a protractor and found the angles that would best reflect the light from the center of the lamp... this is what i came up with.

 

IMGP1285.jpg

 

In all, the relfectors cost me $20 for the mirrored aluminum, plus time to bend them, which was pretty quick.

 

Jesse

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reefman23
Wow, that approximates a parabola with geometry and is shiny metal... *cough*

^_^

 

Yep!

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jeremai: I am open to all donations and I take paypal! Maybe I should start a "hey people, give me free $$" thread like that 15yr old did last week. :P

 

I copied the angles from the ahsupply.com reflectors and made my own... Used simple drawings with a protractor and found the angles that would best reflect the light from the center of the lamp... this is what i came up with.

 

It looks like this is what you copied off AHSupply, correct?

 

36402.jpg

 

In all, the relfectors cost me $20 for the mirrored aluminum, plus time to bend them, which was pretty quick.

 

Do share where you found the materials and how you bent them. I know this isn't a DIY thread, but it is certainly pertinent to the discussion.

 

It looks like you also just used the standard clips to hold the lamp. Do you have spacers under the clips to hold the lamp near the focal point of the reflector?

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Charlie97L
I have visions of tinfoil stapled to cardboard.

 

i have visions of that catching on fire.

 

i have parabolics on my MH and T5s, and white on my pc's in my other tank, and i've run flat before too. parabolics are the way to go, definitely, with mirrored metal.

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reefman23
It looks like this is what you copied off AHSupply, correct?

 

36402.jpg

 

Yeh... that is what I used. Then I just expanded it to my size requirements.

 

Do share where you found the materials and how you bent them. I know this isn't a DIY thread, but it is certainly pertinent to the discussion.

 

I got the metal from Jeff's exotic fish here in So. Cal. Their website is www.exoticfish.com . You will most likely have to email them and have them order it for you. It is just a 24"x24" sheet of polished aluminum thatis designed for a DIY mogul MH fixture (It comes with four little holes in one end).

 

It looks like you also just used the standard clips to hold the lamp. Do you have spacers under the clips to hold the lamp near the focal point of the reflector?

 

Exactly. I used little washers.. i think three... to put the center of the MH lamp in the focal point... as best I could at least. But as far as the PC's go, I just mounted them using the standard metal clips because that is what the reflector on ahsupply.com is designed to be used with. No modifaction necssary there.

 

Jesse

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... www.exoticfish.com .

 

I sent them an email requesting details on the 24"x24" sheet.

 

How did you bend yours?

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D'oh!

 

I wonder if anyone at my work knows someone with a sheet metal brake. If not, I am SOL.

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reefman23
D'oh!

 

I wonder if anyone at my work knows someone with a sheet metal brake. If not, I am SOL.

 

If you cant find one, the aluminum is very easy to crease. You would just need to use a straight-edge of some sort and bend it as straigh as possible. Obviously it is much easier with a bender.

 

Good luck.

 

Jesse

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  • 6 months later...
Very cool! Thank you for the link!

 

Mr. Fosi-

 

So what happened???? Did you do it?

 

I am looking at something to increase also... stuck a piece of mylar below bulb and saw a considerable increase of directed light. not sure which way to go, Also understand the critical angle for light to refract into water is 53 degrees angles greater than that will simply reflect.... and trying to squeeze 4 bulbs in tiny space

 

-R

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mybuickskill6979

i was just thinking to my self why don't peole use mirrors for reflectors then i saw reefmans reflector and said holy cow lol!!

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