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post #1 of 17 (permalink) Old 06-09-2011, 10:01 PM Thread Starter
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Want to build diy t5no fixture

I want to build a diy light for my 55g. I currently have a diy cfl/shoplight fixture with 6 bubs. I like the way it looks, and the plants seem to be doing well. But, it produces a little more heat than I'd like and it takes up too much room in my canopy. So, I want to do something with t5's. I don't want to go ho, because with my canopy there's no room to raise the light. Also, I don't have co2 and if I ever do add it, it will be a while. I'm thinking 2 (maybe 3) t5no bulbs will be good. I am having a hard time resisting picking up the $35 48" twin bulb t5 light from Home Depot and calling it a day. The main thing holding me back is the lack of any kind of reflector. I know a good reflector can make a lot of difference. So, I am thinking of building my own light. I am looking for tips on what to use. I know I'll need a ballast (have read workhorse 5 is good) and end caps. But, what about the reflectors? The ones that I have seen are like $20 ea. and I need one per bulb. If they really cost that much it would be cheaper to buy two of the fixtures from HD. I know the lighting wouldn't be as good, but there would be more light to make up the difference. Thoughts?
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post #2 of 17 (permalink) Old 06-09-2011, 10:31 PM
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You can make a good reflector from thin aluminum sheet, in a \__/ shape, if you can figure out a good way to mount it under the bulbs. Something like that can double the amount of light you get from a twin tube T5NO bulb. You don't need a really fine polished surface on the aluminum, just a shiny one. As I recall, those HD T5NO light strips leave very little room between the bulbs and the metal housing, so it could be difficult to make it work. If you try this, please do post a thread about hit here.

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post #3 of 17 (permalink) Old 06-09-2011, 11:12 PM Thread Starter
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I had considered getting the light from HD and adding a reflector, but I saw a post somewhere (no idea where) where someone did that and wasn't happy with the results. He/she estimated the output to be about half that of the Coralife twin t5no fixture (which apparently has been discontinued) I guess what I am wondering is if there an affordable stand alone reflector of decent quality that I can use in a diy set up.
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post #4 of 17 (permalink) Old 06-09-2011, 11:38 PM
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Originally Posted by PamAndJim View Post
I had considered getting the light from HD and adding a reflector, but I saw a post somewhere (no idea where) where someone did that and wasn't happy with the results. He/she estimated the output to be about half that of the Coralife twin t5no fixture (which apparently has been discontinued) I guess what I am wondering is if there an affordable stand alone reflector of decent quality that I can use in a diy set up.
Individual high-polish T5 reflectors seem to go for around $17-18 + shipping - each - at the low end. For a 4' tank, anyway. Aluminum flashing will be cheaper, and if you don't have flashing but can build the form for it, covering it with unwrinkled aluminum foil will do the trick.

The key to beating out Coralife reflectors will be to make sure there's more room behind, between, and around the bulbs.
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post #5 of 17 (permalink) Old 06-10-2011, 03:00 PM Thread Starter
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If I use the flashing do I need to make one for each bulb? Or can I do one for both bulbs?
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post #6 of 17 (permalink) Old 07-02-2011, 06:24 PM
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Mylar is cheap and damn near reflective as high grade German polished aluminum. It also doesn't trap heat like aluminum foil and aluminum sheet metal/ducting. Might try making a foam fixture and carving a good angle into it and then coating it in mylar. Won't have that heavy professional feel to it but should work and look fine.

Also keep in mind that CFLs are compact directional T5HOs. If you've been running CFLs you can likely run the equivalent amount of T5HOs without changing anything. You could always just add some computer fans to exhaust your CFL fixture - what I plan on doing to the CFL hood I just built.


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post #7 of 17 (permalink) Old 07-02-2011, 09:36 PM
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Originally Posted by ReluctantHippy View Post
Mylar is cheap and damn near reflective as high grade German polished aluminum. It also doesn't trap heat like aluminum foil and aluminum sheet metal/ducting. Might try making a foam fixture and carving a good angle into it and then coating it in mylar. Won't have that heavy professional feel to it but should work and look fine.

.
I have tested mylar as a reflector, and was amazed to find that even flat white paint is a better reflector. Mylar gives an accurate reflection, like a mirror, but most mylar has too thin an aluminum coating to reflect nearly all of the light. You can see through most mylar - meaning that some light can pass through it and not be reflected. By contrast, plain aluminum foil is an excellent reflector, and even crudely polished aluminum sheet is good.

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post #8 of 17 (permalink) Old 07-12-2011, 04:44 AM
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I have tested mylar as a reflector, and was amazed to find that even flat white paint is a better reflector. Mylar gives an accurate reflection, like a mirror, but most mylar has too thin an aluminum coating to reflect nearly all of the light. You can see through most mylar - meaning that some light can pass through it and not be reflected. By contrast, plain aluminum foil is an excellent reflector, and even crudely polished aluminum sheet is good.

I too have tested the reflectivity of mylar versus white paint, polished aluminum reflectors, and tin foil and have found different results. Mylar made and sold for reflecting light when backed by another material will let no light penetrate through it and is on average 2% more reflective than the higher reflective white paints - without backing is another story but I would hope no one would make a reflector out of mylar alone. Polished aluminum reflectors reflect around 95% of the light, mylar ~92%, white paint 90-82%, and aluminum foil around 85% (I've seen these figures all differ by about 3% but they have always remained in that same order which also correlated to my findings). Can't possibly see how it would matter on aquariums but aluminum foil is the most likely to form hot spots and the least likely (unless crumpled beforehand) to evenly disperse the light.

I've used aluminum foil more than I would like to admit and it definitely does the job but I would recommend any of the other alternatives. I think crudely polished aluminum works great and is really easy to work with.


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post #9 of 17 (permalink) Old 07-13-2011, 07:35 PM
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IVe always been under the impression flat white paint is the most reflective surface?

i know i had a link to some graphs, reasearch, fancy talk somewere....


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post #10 of 17 (permalink) Old 07-13-2011, 08:32 PM
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I'll always look for any real research into the stuff that gets repeated over and over on forums. Trev, any links to actual data you found would be great.

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post #11 of 17 (permalink) Old 07-14-2011, 12:36 AM
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I too have tested the reflectivity of mylar versus white paint, polished aluminum reflectors, and tin foil and have found different results. Mylar made and sold for reflecting light when backed by another material will let no light penetrate through it and is on average 2% more reflective than the higher reflective white paints - without backing is another story but I would hope no one would make a reflector out of mylar alone. .
If light goes through mylar to a backing material, how does that help anything? The light has to be reflected by the aluminum coating on the mylar or it isn't reflected at all. Sorry, I don't buy this.

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post #12 of 17 (permalink) Old 07-14-2011, 03:49 PM
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If light goes through mylar to a backing material, how does that help anything? The light has to be reflected by the aluminum coating on the mylar or it isn't reflected at all. Sorry, I don't buy this.
If you peel up most white paint and hold it up against a light you can see the light through it - even the nasty old school super thick lead paint. I'm working on getting my lux meter back at which point I'll try and upload some comparison pics.

Here's a blurb from an indoor grow magazine -

" Choosing the right surface for the walls of your grow room is very important, as up to 40% of your total yield comes from the edge, and the right wall surface can increase the amount of light those plants receive by up to 30%! Artificial lighting diminishes exponentially with distance, so it is important to ‘contain’ as much of this light as possible, and direct it accordingly. Reflective surfaces also help illuminate the lower portions of the garden, providing lower buds with light and heat energy.

To get the best results with your light and walls, it is important to get the walls as close as possible to your garden to ensure the least amount of light is wasted. As a caveat, the percentages provided are only useful as a general guideline, as they present the range of reflectivity of the particular surfaces. The high percentage presents the best possible circumstances for that material (for example a 99% reflectivity rating for mylar sheeting would be under ideal conditions - no creases, completely flat, no discoloration, etc).

The best way to determine how well your grow room walls reflect light would be to purchase a light meter and measure your light directly; then take an opaque board and hold it a few inches off one of your walls with the light meter below the board in such a fashion that the light reflects off the wall and onto the light meter. You can then compare the difference between the two and determine a percentage from those numbers, the closer the two numbers are, the better your wall reflects light. It is important that in both measurements, your light meter is the same distance from the light, otherwise your results will be skewed.

Also important to note is that radiant light energy refers to electromagnetic (EM) radiation with a wavelength between 400-700 nanometers (nm) and radiant heat energy correlates to EM radiation with a wavelength between 800-2000nm.

Listed below are some of the most commonly used materials used for grow room walls:

Foylon:

A more durable version of mylar, made of spun polyester fabric and reinforced with foil laminate. Foylon is resistant to most solutions, won't tear or fade, and can be wiped or washed clean.

A great solution for growers who are interested in long term use, and though it may be slightly more expensive than mylar, its durability will more than make up for its cost. It has the ability to reflect about 95% of the light and approximately 85% of the heat energy, so a good ventilation system should be used in conjunction with folyon.

A recommended method to attach Foylon to the walls would be using Velcro, as it makes taking it down for cleaning much easier nd reduces the risk of tearing, creasing or bending it. If this is used for your walls, making sure you get it flush with the wall with no pockets of air between it and the wall to prevent hotspots.

Mylar:

A highly reflective polyester film that comes in varying thickness, the most common being 1 and 2 mm thick. The 2mm thick mylar while not quite as durable as the foylon, is fairly rugged. The 1mm thick mylar tears fairly easily, so taking it down for cleaning is quite difficult without damaging it in the process. Both types of mylar are able to reflect approximately 92-97% reflective, giving it the potential to be more reflective than foylon, but because foylon is more easily cleaned without damaging it as well as it being harder to crease, foylon usually ends up being slightly more reflective. Important to note is that mylar reflects radiant heat energy just as well as foylon (around 85%), so proper ventilation is necessary if mylar is used in your grow room. Attaching this to walls can be done in a similar fashion as foylon, and the same caution should be used to avoid creating hotspots in your room. The 1mm thick mylar stands a fair chance of being creased or ripped in the process unfortunately, even if Velcro is used to attach to the walls.

C3 anti-detection film: (I'd sleep better at night if I had this.)

A specialized type of mylar that exhibits the same properties as the 2mm thick mylar, but in addition to reflecting approximately 92-97% of the light, it also is 90% infrared proof, making your grow room all but invisible to IR scanning. This can also be attached in the same manner as foylon or mylar, and the same caution should be used to avoid creating hotspots in your room.

Flat white paint:

Self explanatory; a great option for large grow rooms or for people who are interested in a low maintenance wall. Flat white paint has the ability to reflect between 75-85% of the light, and does not create hotspots. Adding a fungicide is recommended when painting.

Glossy and eggshell whites not reflect light as efficiently as flat white. Semi-gloss paint for example, only has the ability to reflect between 55-60% of the light. Also important to remember when using paint is that any smears or blemishes on the surface take away from how reflective the wall is so care should be taken to avoid marking or staining the walls. Titanium white paint is very reflective; however it is usually only used on reflectors due to its high cost.


White/Black plastic (also known as panda plastic or "poly"):

"Poly" is useful if you are setting up a temporary grow room or don’t want to damage the walls. Poly is easily cleaned.

The purpose of the black side is to not allow any light to pass through the plastic, which ensures your dark cycle remains dark. The white side is 75-90% reflective. Choose a 6 "mill" thickness of poly for maximum light blockage and duribility.

If this plastic is put too close to the light, you will obviously melt it so be careful!. Panda plastic does not create hotspots. Poly can be attached to the walls by using carpenter’s nails or using tape glue or similar means. This can be used as a cheap alternative to mylar if painting your grow room is out of the question.

Polystyrene Foam Sheeting (more commonly known as Styrofoam):

This is excellent for harsh environment growrooms (your attic for example), provided you have a good ventilation system and a way to keep the temperatures from rising too high (an a/c unit or similar) as it is an excellent insulator.

It is also a great material for use in a temporary setup or for use as a "travelling reflector" on a light mover, where weight is a concern. It is approximately 75-85% light reflective so it is comparable to using a flat white paint. Foam will not create hot spots. Rigid foam can be purchased in sheets, and can be used as a free standing wall or can be taped, glued or nailed to the wall, the last generally being the most successful method.

Emergency Blankets:

These are ultra thin polyester blankets that are sold in most camping stores and are constructed of a single layer of polyester film that is covered with a layer of vapor deposited aluminum.

It is not very effective at reflecting light because it is so thin. Holding it between you and a light source, many small holes are noticed at the intersections of creases and the entire blanket is translucent to begin with, this coupled with the many creases that are in it when you purchase it takes away a significant amount of it reflectivity. It is very easily creased as well which also detracts from its ability to reflect light. And while it is reflects nearly 90% of radiant heat energy, it is only able to reflect around 70% of the light.

The largest advantage of using this type of material is that it is very cheap and therefore easily replaced. Emergency blankets can create hotspots if not attached flush to the wall so it is important that no air gaps exist between it and your supporting wall. The easiest way to attach this is to use tape (Aluminum or metal tape is recommended), as it tears very easily once it is cut or punctured.

Aluminum Foil:

Aluminum foil is no more than 55% reflective - if used, make sure that the dull side is the one that is used to reflect the light. When it becomes creased its reflectivity is even lower (around 35%.) It is also very dangerous to use because it creates hotspots easily, is electrically conductive, and is a fire hazard when it is in close contact with HID lighting. Attaching this to walls is a pain and usually using aluminum tape or glue is the best way. This should only be used as a last resort, and even then its usefulness is questionable.

"



To the OP, check this stuff out. Probably the best you can get and really easy to work with. OOps I lost the link. You can find dimpled polished aluminum sheets for pretty cheap. Same exact stuff they use to make high grade reflectors.


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post #13 of 17 (permalink) Old 07-14-2011, 04:25 PM
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Super simple test.

Light in reflector:


Light with a piece of white paper on top:


Light with a sheet of mylar with no backing:


mylar with the same sheet of paper backing it:


Mylar like you said was terrible with no backing. But backed by just a piece of white paper and no light comes through even though the light had no problem going through the paper.

Now white paint:

Tried to put it on nice and thick:



Not to great:



1/4 just paper, 1/4 with white paint, 1/4 with white paint and mylar, 1/4 with just mylar:



Notice along the edge of the mylar where it isn't flat up against the paper? Light goes through it and the paper. But when right up against backing nothing escapes. Unless the light is being trapped between the two layers and getting stuck there (in which case it would get really really hot - essentially a 23w heater and I still think it would be visible) then the mylar seems to be the most reflective of those but only when coupled with a backing material that isn't translucent.

/e I'm putting two more coats of white paint and will test again. I'm disappointed it didn't work better as I use white paint often.

Three thick coats of titanium white paint (one of the more reflective whites being rated at 84%)



Compared to just the paper:



The two compared to mylar:



I should include that this is the cheaper 1mil mylar versus the preferred 2mil


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Last edited by ReluctantHippy; 07-15-2011 at 02:17 AM.
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post #14 of 17 (permalink) Old 07-15-2011, 01:28 AM
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There is a lot that is just wrong about that article you quoted. I know for sure that aluminum foil is never going to reflect only 55% of the incident light - off white paper would reflect more than that. Then, the suggested way of testing reflective surfaces is technically very wrong. It assumes that light that doesn't pass through the material has to be reflected. Try using black construction paper. That reflects a very small amount of light (that's why it is black) but no light comes through. Light can be absorbed, reflected, or transmitted.

My testing was simple and direct. I had a light fixture on which I could cover the reflector with various materials. I used a PAR meter to measure how much light reached the "target". I used a piece of paper, spray painted with a can of white paint I happened to have, a piece of aluminum foil, and a piece of 3 mil aluminized mylar. The best reflector was aluminum foil, second best was the white painted paper, and third was the mylar. The differences were not great, but were well beyond experimental error. I have since found that it makes little if any difference which side of the aluminum foil is used - aluminum is inherently a highly reflective material for all wavelengths of light, down into the infrared region. It makes no difference whether or not the alumiinum foil is wrinkled. Also, I found later that I could double the light from a horizontally mounted screw-in CFL bulb by using a DIY reflector, made of thin aluminum sheet, shiny, but not polished, in a \_/ shape. I didn't try other materials that time.

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post #15 of 17 (permalink) Old 07-15-2011, 01:41 AM
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The article was describing how to measure the difference in reflectivity of surfaces not the brightness at canopy level or substrate level - the materials were not meant as part of a reflector but instead to line an entire room. I believe he is correct in measuring the lux of a surface not receiving direct light but only reflected light - no point in measuring direct light when only comparing reflectivity of the surface material. I can point to other articles though that just compare measurements of lux at surface levels but most of them are comparing different materials along with different reflector designs and to be honest no one in that industry uses mylar, white paint, or foil for the primary reflector as they would either burn the plants (the foil) or be a fire hazard.

My test was merely to show that backing mylar greatly changes how it functions - same as paint. Your 'light passes through it and it is thus not very reflective' argument is obviously not valid unless paint is not reflective either. Do you think my 1mil mylar was absorbing the majority of my light (but only when backed)? This would be a strange phenomenon, no? I wish I had a digital temp gun to show you the differences in temps between the plain paper against the light versus the mylar and paper - if the mylar is absorbing that much light the surface would definitely be much much warmer, which it is not.

I agree that off white paper reflects more than aluminum foil. Remember that light can be absorbed and transmitted and then think of what aluminum foil is commonly used for (reflecting, absorbing and transmitting heat - does the first the best but the others as well). But keep in mind gray/off white paint reflects ~73% of light (at least according to my lighting software used in most building designs) so being worse than off white paper doesn't mean its garbage.


Out of curiousity how was the piece of white paper and the mylar attached to the reflector? Did you use a spray adhesive so that they were right up against the natural reflector material? If not I would say your results are due to there being a gap between both the white painted paper and the reflector and the same with the mylar. I have a REALLY hard time believing that aluminum foil is more reflective than two different industry standard light reflecting materials - why wouldn't it be the new industry standard?


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Last edited by ReluctantHippy; 07-15-2011 at 03:23 PM.
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