Mirror

[pocilipora]

Can you use miror, cut into a reflector shape, for metal halides. Is there a chart any where that I can look at? Something that compares reflective materials?

[StirCrazy]

a Miror is very reflective but it will also duplacate hot spots as it does not difuse the light at all.. what seams to work good for MH bulbs is a shiny white reflector (ie gloss white paint in your hood, or white sheet metal) or if you can find it hammertone aluminum. if you are talking floressents it would be good as floressent light is already difused so why difuse it anymore.

some people feel that a miror will take away light (because it is going through glass first) but the amount of light that it filters is not realy measurable by our standards but the problem I do find with a miror is that high heat will cause most to delamanate and you will get dark non reflective spots so use on a MH would be short lived because of the heat.


Steve

[Canadian]

Ummm...I call bull$hit on Steve's comment about diffusing MH lighting. Steve, this is one of those cases where your lack of experience in reefkeeping and minimal "research" being espoused as if it is fact, is in fact incorrect and has the serious potential of leading "newbies" astray. Yes, as Richard Harker has pointed out, highly reflective material in conjunction with MH lamps will not do anything to diffuse "hot spots." And yes, the use of a white reflector would indeed diffuse these hotspots. However, a white reflector would seriously diminish the intensity of light entering the tank (when compared to polished materials), and considering MH lighting is not as intense as we would like our lights to be (i.e. in an attempt to replicate the sun), all hobbyists are better off maximizing their intensity and secondarily paying attention to diffusion of light. Therefore, as per Sanjay Joshi's suggestions: use a quality parabolic reflector of some sort in conjunction with MH lighting to ensure that intensity is adequate.

Now, in regards to your question about using a mirror as a reflector: There are two reasons for not doing so: 1) If and or when humid air makes its way behind the mirror, it will tarnish the mirror and it will turn black. 2) Mirrored glass that close to a lamp is at serious risk of becoming extremely hot and could potentially shatter (under a variety of circumstances) due to the proximity and heat of the MH lamp. Clearly, it would not be an especially enjoyable day if you had to pick glass shards and splinters out of your reef tank. And the use of mirrored acrylic and other mirrored plastics is obviously not a possibility as they could melt and become a fire hazard.

With that said, there are a few people who have experimented with the idea of using mirrored tiles glued into their hood thus ensuring no water could contact the back of the mirror. You might want to check on RC (I believe there were a few of them there), and ask them about their experiences.

[reefburnaby]

Hi,

Yah...using mirrors to build a reflector can work...but MH tend to be very hot and they can shatter the mirror if water is splashed on to it. So...it is a bit more risky.

As for the diffuse vs specular, it is your choice. Both will work, but it is much harder to build a DIY specular (shiny) reflector properly than it is to build a diffuse (white) recflector. The white reflector - just bend it in to any shape you want and it will work 95% of the time. While a shiny reflector requires a bit of more planning -- there is a chance that it will be better than a white reflector, but there is also a chance that it is much much worse.

Hope that helps.

- Victor.

[StirCrazy]

Canadian, I am glad we have you here.. what would all us that don't know anything do with out you? damn I am awed in your presence..

I would love to read you book as you seam to know it all.. what is the title?

[pocilipora]

Thanks for the Heated replys, Ive done some reading and I think Im going with the Spyder Reflector.

[Canadian]

The title of my book is "Everything I've Learned From Actual Hands-on Experience and an Education: Things Steve Doesn't Have." You can pick up a copy at Chapters while you're there getting a copy of "English Grammar for Dummies."

Steve, you don't want to go down this road of fire with me...trust me...you'll end up with 3rd degree burns.

LOL!!!!!!!!!!!!
This is really funny, comon now guys, shake hands and go back to class...

I like parbabolic and spyder reflectors myself, but Ive used the "high heat reflective mylar" when I needed to make something reflective.

[Troy F]

Let's keep it clean guys. I think what touched Andrew off was that a "shiny white reflector" is not "what work's best" and is in fact a poor choice for reflector. I believe either Dana Riddle or Sanjay Joshi stated that a mirror would be the ultimate reflector were it not for the difficulty in application.

I too look forward to Andrew's book, if it is even half as colourful as he is it should be a good read. Of course you could just wait for the movie [img]images/smiles/icon_wink.gif[/img] .

[Troy F]

Damn, I was typing my last response and you guys fire off another couple. Be nice damn it.