DIY reflectors

[catshanon]

Hi there people,

I really want to grow HC cuba in my tank and at the same time I don't want to invest in ready made lighting. I am planning to buy some T5HO lights and make reflectors for them. As I recently found out, reflectors play a major major part in the amount of light that is going down into the tank. After searching some forums, I found out about ahsupply.com . People have good reviews about their reflectors and they use mirror polished aluminium sheets for their reflectors. Specifically, they use MIRO-IV aluminium sheets. There is a distributor in Ontario that sells these sheets (anomet) . A silver finished sheet (0.020" x 48" x 24") with 98% reflectivity will cost $55 and $42 to ship to Alberta.

I was wondering if any other members are interested in building their own reflectors. Built properly, reflectors can increase the amount of light going into the tanks many many times. proper reflector design. If anyone has worked with aluminium sheets before, please let me know how difficult it is to cut them (0.020" thick) and what tools I would require to cut and shape them.

Thanks in advance,

Raj

[jewels]

(0.020" thick) and what tools I would require to cut and shape them.

Thats a half millimetre - a good pair of scissors would almost do it.

[African_Fever]

Doesn't FLAT white paint have a high reflectivity, somewhere over 90% if I remember correctly from a couple of years ago when I was doing my DIY canopy. $10 for a can of paint versus $100 for a reflector wasn't worth it to me at the time...

[jvision]

Kyle's right. For the money, flat white paint is the best reflector for the DIYer - I learned this years ago from guys using light meters.

[catshanon]

Doesn't FLAT white paint have a high reflectivity, somewhere over 90% if I remember correctly from a couple of years ago when I was doing my DIY canopy. $10 for a can of paint versus $100 for a reflector wasn't worth it to me at the time...

White paint does have high reflectivity values, but I just found out that there are 2 kinds of reflection.. diffuse reflection and specular reflection. Diffuse reflection will make the incident light (light falling on the material) go in a completely different angle, whereas specular reflection will bounce of the material at a same angle as the angle in which the light came in. Hence the need for well made designs for the reflectors built of specular material. Here is a good link to show that:

specular reflection

Here is a discussion about white paint and mylar and other materials. I have cut and pasted from the source and the link to the source is at the bottom.

The total reflectivity of a good white paint nearly equals that of

silver, and is certainly better than any aluminized surface (mylar,

foil or sheet metal). The difference between a diffuse (flat white or

brushed metal) reflector and a specular (polished metal or mirror)

reflector is the direction of the reflected light.

Over water, that just might have some effect, for light nearly

parallel to the water surface is reflected away, while 96% or so of

that incident nearly directly on the water does penetrate and go on

into the water.

Diffuse reflection scatters in all directions, so some of the light

must go back toward the tube or off at a shallow angle. Really

efficient specular designs (The McDonald's Golden Arches cross

section, for example) could, in theory, direct more of the light in

proper directions to go into the water better. Be sure and re-polish

them weekly, though. :-)

White paint has the huge advantage that the *shape* of the reflector

is totally non-critical, where shiny reflectors need careful

shape-control for any real efficiency advantage.

discussion about white paint vs other materials

[African_Fever]

From reading the above cut-and-paste, I get the impression that for the regular DIY'er flat white paint is the way to go, because if your reflector isn't designed EXACTLY correctly (and maintained/cleaned regularly) you won't get the full benefit of going that route. Due to the diffuse nature of flat white paint, you can basically make a box to hold your lights and fit over your tank without worrying about the angles of the reflectors and how difficult that can be to get perfect.

[jvision]

If you don't want to lose light w. flat white paint, you could build a complete canopy (box w. lid). More light would be directed back into the tank eventually.

[outacontrol]

You can buy T5HO strip lights for reflectors already made from most lighting wholesalers. We have been using them for a few years already in large buildings instead of metal halide highbay lighting. Much easier and probably cheaper way to go, than building your own.

[catshanon]

I gave it some thought and building the reflectors exactly is out of the question. The Tek reflectors had 10 angles in it while the newer TekII has 29 angles. Without a metal press, this will be impossible to achieve. So, I will order a retrofit kit from JLAquatics. They have a Sunlight supply T5HO kit for $132...

Which brings me to my next question...Where can I get T5 moisture proof endcaps and mounts in Edmonton. Will Home Depot or Litemore carry them. I am just putting together a list of the materials that are in the kit to see if I can get them cheaply. Then I can just order the reflectors and bulbs from JLAquatics and save some cash.

Thanks in advance,

Raj

[jvision]

A little dab of silicone beneith the tombstones should do the trick. As for waterproof endcaps, I did a quick search and MOPS (Mail Order Pet Supply) carries them.