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#1
12/06/2007, 04:34 PM
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Mylar in a MH reflector..?
I'm considering using mylar to give my reflector more efficiency. How does mylar hold up under heat and light? Will it yellow, dry, crack, crinkle, etc. over time? Or does it last pretty long? Are there any other issues with using mylar in a reflector?
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#2
12/06/2007, 04:51 PM
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It will not hold to heat. I used aluminized mylar tape to create a reflective surface for T-12 VHO Although the heat did not melted or ellowed the mylar, the aluminum separated from the mylar and got all cracked up.
THere is a duct tape that is made of aluminum foil and tick enough to be able to handle well, that will work as a good reflective surface.
__________________
Did I write what I wrote? What the heck am I talking about! Well..... Nevermind. |
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#3
12/07/2007, 04:08 PM
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i'm going to make my own reflectors and i think im going to use this stuff http://www.millworkforless.com/skylights-suntunnels.htm for mine. Im going to get some of the tunnel extensions for like 30 bucks and make them out of that. Its supposed to be like the stuff that lumenarc uses for theirs. Let me know what you guys think.
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#4
12/07/2007, 04:42 PM
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I hear that's a good way to go. But my problem is the cost. I wanted to make sure it'd all work before I just drop $40-$50 on a tube to make reflectors. The aluminum flashing I used was only $10 for enough to make 4-5 reflectors.
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#5
12/07/2007, 06:29 PM
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The problem is that you will not be able to build something that comes anywhere close to the efficiency of a well designed reflector. The reflective properties of the material are only a secondary consideration. The first consideration is the exact shape of the reflector. The shape dictates how much light can be moved to the desired focus area.
If you MUST DIY then your only sensible option is to build a lumenarc knock off. Otherwise, you will be losing a majority of the light to scatter, restrike and poor angles if incidence. |
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#6
12/08/2007, 01:58 PM
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I agree that efficiency is lost without using high-reflectivity aluminum, Bean. But I don't plan on keeping SPS anytime soon, and my tank's only a 40BR, so it's not like I absolutely require the most efficiency possible out of my lighting. I would think that the dual 175W MH's over my tank might make my moderate-light LPS and softies (like my acan) a bit unhappy if I got maximum efficiency from my reflectors. In any case, they've GOT to be better than the crappy flat reflector I got with the bulbs in the first place. These should be more than enough for what I need.
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#7
12/09/2007, 11:43 AM
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I would not be so sure that they will be better.
Nonetheless, my point is more along the lines that a single 175W in a good relflector would be able to do the job of two 17W in a DIY reflector  I also want to make sure that others following along understand the limitations. You appear to so in the end, if you get enough light to be happy with your project, that is all that counts. |
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#8
12/09/2007, 12:02 PM
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If you can make a decent canopy and don't have the room for reflectors, Mylar works great.
You can buy it buy the roll on ebay, 25' all the way to like 100'.
__________________
Knowing something is having first hand experience - Me Having a high post count doesn't necessarily show intelligence or knowledge, it simply shows you just talk a lot. - Me |
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#9
12/09/2007, 01:14 PM
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I found some silver thermal tape at the local Menards and used it in a nano set-up. It worked like a charm and held up to the heat of a 250w HQI. It has incredible reflective properties and was easy to use. Just my $.02.
__________________
"courage is not the absence of fear - it is the presence of fear and the abillity to carry on" |
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#10
12/09/2007, 01:32 PM
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Guys, it is more about the shape of the reflector than it is the reflective properties of the material.
I suppose a 250 with no reflector would be more than enough for a nano! Jared, a canopy with a mylar lining will not come close to performing as well as even the worst retrofit reflectors. |
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#11
12/10/2007, 05:07 PM
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Bean, it seems you must know quite a bit about this type of thing. So, would you recommend using mylar or white paint inside a DIY reflector to get the most out of it without polishing it to a mirror finish? My guess is that white paint is best. But I could be wrong.
I think a lot of this "maximum efficiency" stuff is great for people trying to squeeze all they can out of something for larger systems containing SPS and other similar items that require as much of something as we can give them. I'm just not as worried about squeezing as much out of my lights as I can, simply because I know that these reflectors can't be worse than the simple, flat reflector I got with these lights. There's nothing on the sides to point light down, and the ends were open, so light shoots out both sides. Maybe spider reflectors would be a good step up, but even those lose a lot of light out the ends. Either way, I lose a LOT of light from a flat or open-ended reflector, even if it is much more efficient material being used. I figure, at least I should get more even light distribution using this Lumenarc™-style reflector. And even the best reflectors can get dirty from salt creep or splashing water and corrosion, which reduce their efficiency, too. Just as reference, here's a pic of the crappy reflector I got with the lights when I bought them. Maybe it's not that bad, but I wasn't overly happy with it, so I figured I'd give building one a try.  And here's my reflector "prototype" as-is with no mylar or paint:  
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#12
12/10/2007, 07:35 PM
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Just leave the DIY lumenarc as it is. You will have a hard time getting any coating to stick to that surface anyway.
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