Better reflectors

[richkel]

Hi gang,

Check this out. It's a polished stainless steel bowl, 18" diameter, 8 bucks at a kitchen supply site! I'm going to use it for a CFL reflector. When I look at various lighting set-ups, it seems like a lot of light is wasted lighting the space, not the plant. Eventually I want to make a CFL fixture with a parabolic reflector and extension that gets lowered around a plant sort of like a hair dryer. It would have slots and a muffin fan on top to cool the lights and bring air up through the plant. The plant would be topped and shaped to fit the fixture. Anyone else working along those lines?

Rich

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[Blaze4daze]

What a cool idea. Who would of thought of using a SS bowl as a reflector, a little modifying and that seems like it would be perfect reflecting the light back down around your plant. Please let us know how it works out. A home~made reflector for $8, Nice.

[Saturnalia]

Hi Rich. Be careful that this reflector does not make hot spots by focusing the light. If you look at some of the reflectors available to buy online you will see that the surface is not smooth like your bowl but textured with a kind of dimple pattern. This diffuses the light evenly and smoothly, avoiding hot spots.
Maybe if you spent some time with a small hammer just lightly dimpling the surface it would be more efficient?
I like your idea of shaping the plant to fit. Remember the inverse square law and try and get as much of the canopy as near to the light source as possible.

[richkel]

The dimpling on reflectors is one of the things I don't like. It scatters the light instead of directing it towards the plant, but yes, I'll have to watch for hot spots.

My figuring is what you want most is light directly from the bulb to the plant. Because CFLs can be put close, they have a wider angle of direct light to plant, still less than 50% though. Next best is one bounce from reflector to plant. A deep true parabolic should be best for that. What's left is light that hits the room and bounces back to the plant. I you look at most HID/reflector set-ups, 10" or more above the plant, there's a lot of light going directly from the bulb to the room. With the angles and distances involved, I suspect the plant never gets much of that, but I'd be curious to read any studies on it.

How about this; A large diameter, spiral CFL, socket on he side, (90 deg from the spiral axis) with a cola growing up through the center and the fan leaves sticking out of the gaps. :-)

Rich

[richkel]

Here's a few variations on the theme. I think there is something to the idea of lighting the plant, not the space. The 18" unit is an $8 bowl, 6-23W CFLs for under a dollar each, and a couple bucks each for the sockets. I ordered a muffin fan to mount on top. So for under $50 I think it's a legitimate grow light.

I went with the 23W cfls because the smaller bubs are the most efficient. At 1600 lumens each that's 9600 lumens. The 18" dia bowl has an opening of 1.75 sq. ft. I figure that gives a direct intensity of 5432 lumens per sq ft which should be decent.

Tip; I picked up a 6 pack of bulbs at Lowes and noticed one was broken. I took it up and they sold it for 1/2 price, less than $1 each for the remaining five. When I wanted 2700K bulbs, sure enough I found another 6-pack with one broken. (No I didn't break it)

[Schmokin]

Haha! You sure you didn't break it ;-)
Nice posts Richkel. There are a lot of folk here who are looking to save a few bucks on the specialist stuff by making their own. Great advice here, keep up the good work.

[richkel]

Here it is with fan and wired. I spaced a center reflector about 1/2" above the hole cut for the fan. I like it! I've seen "bucket" grows with a light on top of a 5 gal bucket. This would be a good light for a garbage can grow. :^)

[Schmokin]

Brilliant! Well impressed. Let's see how it works...