# Reflectors?



## kiwik (Apr 3, 2007)

i have a 10 gallon with two lighting hoods that are 15 watt each. i learned that the white plastic reflectors that come with it are pretty much useless. where can i get more useful reflectors?


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## kunerd (Aug 2, 2007)

ahsupply.com


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## fishstein (Dec 12, 2005)

You can also a) line your white reflectors with reflective mylar, which is highly reflective (like a far more polished version of tin foil) - email me if you'd like some. b) it depends on what kind of bulbs you have - do you have T8 tube bulbs or power compact bulbs etc.? Also, how long are the bulbs?

Also consider whether or not you want to keep a low or high light tank - many crypts and anubias will do fine with the lights you have. Remember that as you up lighting requirements, you also up requirements for ferts and CO2.


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## rs79 (Dec 7, 2004)

I tried the mylar. If you get the heat resistant water resistant stuff not the regular reflective mylar then it's ok for short term - but you really really want the reflectors from ahsupply.


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## fishstein (Dec 12, 2005)

FYI AH Supply, which seems to make nice stuff, doesn't supply reflectors for T8 bulbs. Every parabolic reflector is made for use with a particular bulb in mind - the reflector is maximized for that particular bulb type and size.

Heavy duty mylar (2mm instead of 1mm) will last for many years - you will not damage it in normal use.

That said, well-designed parabolic reflectors made for your particular bulb type will push the most light down into the tank. However, if your goal is just to push more light down into the tank at a low cost, reflective mylar will work fine. I would only use the 2mm heavy duty mylar though.


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## newbie314 (Mar 2, 2007)

I like the mylar idea, but what are you using to glue the mylar. I'm concerned about the heat from the bulbs.

I assume some type of epoxy.
I know glue from glue guns can get a little soft.


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## fishstein (Dec 12, 2005)

Regular silicon aquarium glue has worked fine. I've never had the heavy duty mylar I've applied this way directly to wood come undone. Just apply lines of the silicon glue to the surface and apply the Mylar strips you've measured and precut, and you're all set.


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## hoppycalif (Apr 7, 2005)

AH Supply reflectors are not parabolic and parabolic reflectors are no better than the flat planes used for AH Supply reflectors when you are using thick bulbs like T8 or T12 for example. As the bulbs get thinner and thinner, then a parabolic reflector can make a difference.


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## fishstein (Dec 12, 2005)

Hi Hoppy,

I've learned a lot from your informative posts, but that's not correct. It's readily apparent studying the shape and I've confirmed this with lighting engineers at a major lighting company and a botanist.

Flat-back reflectors, with properly angled sides that come down far enough from the bulb to prevent light from the sides of bulbs striking other bulbs, are better than just plain flat back reflectors with shallow sides. Plain flat back reflectors with shallow sides are not much better than high quality mylar.

In any case, reflectors with flat backs direct light from the back of bulbs right back at the bulb, not into the tank. That's wasted light.

Well-designed parabolic reflectors, and by this I mean v-notch parabolics, with the apex of the "V" in the center of the parabola facing the bulb, and sides long enough to push light down and prevent light from the sides of bulbs striking other bulbs, are far superior to flat back reflectors. It's not even close. And the v-notch parabolic reflectors are superior to regular parabolic reflectors without a V-notch. 

V-notch parabolics take the light from the back of the bulb and direct it sideways, to walls that are angled to push that light down into the tank. All that light from the back of the bulb gets put to good use.

In addition, V-notch parabolics work just as well with T8 and T12 bulbs are they do with T5, AS LONG AS THE SIZE OF THE PARABOLA AND V ARE SIZED UP TO MATCH THE DIAMETER OF THE T8 AND T12. This becomes impractical with the larger diameter T12 but works beautifully with T8 bulbs. And for T8 they have the benefit of allowing the use of a wider array of high quality plant bulbs at far lower cost than T5 as well as lower cost ballasts and other components, because T8 bulbs and equipment are ubiquitous and low cost. T8s are also energy efficient, especially if they are overdriven.

I have verified the superiority of this design with light engineers at a major lighting company and with botanists, and it's common sense. Just draw a picture of a v-notch parabolic behind a bulb. You can see the light strike angles - all the light gets pushed down into the tank - approximately 300% more light than without the v-notch parabolic reflector, if one uses high quality reflector material. Which also means you can grow just about any plants you like with less bulbs and cheaper equipment, which means less electricity, less heat, lower A/C needs and less impact on your wallet + less impact on the environment.


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## Cliff Mayes (Jan 29, 2007)

Fishstein: Do you have specific recommendations for lights and reflectors?

I am using the AH Supply stuff on a couple of tanks and am ready to buy more. Is there a better way out there?

Thanks for your help.


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## hoppycalif (Apr 7, 2005)

AH Supply reflectors are not "flat back" reflectors at all. They are shaped to direct the light from the rear of the bulb to the side and down into the tank. A parabolic reflector will focus the light from a point into a parallel beam, or for linear reflectors, from a line into a parallel beam. But a T8 bulb is an inch thick, far from a line light source. So, if any portion of the surface of the bulb is at the parabola focus, none of the rest of it will be. So, "parabolic" reflectors that are effective for such large area sources are not really parabolic at all, but are a compromise shape that semi-focuses some of the light into a near parallel beam. (The light from the side of the bulb facing the opening of the reflector is not focused at all, because it never strikes the reflector at all.) No question that a well designed curved reflector, with the bulb deep down inside the reflector, is the best shape reflector to use. But, in the real world of affordable reflectors AH Supply reflectors are very nearly the best available, if not the best.


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## helgymatt (Sep 12, 2007)

I have 2 shop lights over my 55 gallon that have t8 bulbs in them (4 bulbs total). Each bulb is overdriven 2x. The shop lights have white paint as a reflector. I do seem to get good growth with this light set-up, but I think I could do better. I do not want to switch to a different light set or reflectors because I have already spent a lot of money on light strips, ballasts, and bulbs (and now I'm an even poorer college student...planted aquariums was the wrong hobby for me to get into.) Anyway, would I benefit much from putting mylar on the shop lights, or would it be a waste of my time and money?


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## trag (Jan 9, 2008)

fishstein said:


> V-notch parabolics take the light from the back of the bulb and direct it sideways, to walls that are angled to push that light down into the tank. All that light from the back of the bulb gets put to good use.
> 
> In addition, V-notch parabolics work just as well with T8 and T12 bulbs are they do with T5, AS LONG AS THE SIZE OF THE PARABOLA AND V ARE SIZED UP TO MATCH THE DIAMETER OF THE T8 AND T12.


I found this design http://www.thevideodoc.com/Images/T-8DualReflector.jpg in a forum posting here http://www.homediscussion.com/showthread.php?t=150843&page=3 look about the middle of the page. This guy has put up a nice design for a T8 based dual reflector with the V-notch. If you scale all of the dimensions by 5/8 it will work for a pair of T5 bulbs. He also has an animation of the light reflection posted. And there's a design for a single T12 reflector, again scale by 2/3 for T8 and 5/12 for T5.

I have sections of 5" X 48" mirror surfaced stainless steel which I plan to bend into those shapes for T5 reflectors. I'm not making fast progress on the project though. Too much other stuff to do at home.


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## trag (Jan 9, 2008)

newbie314 said:


> I like the mylar idea, but what are you using to glue the mylar. I'm concerned about the heat from the bulbs.
> 
> I assume some type of epoxy.
> I know glue from glue guns can get a little soft.


Some folks have used the 3M Super 77 Spray Adhesive available in the paint department at Home Depot to attach mylar to other surfaces. However, if your store carries it, the High Strength 90 from 3M is rated for higher temperatures than the Super 77. It does cost about $3 more per can, than the Super 77.


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