Confused on terrarium lighting hoods

[lund0682]

This is really interesting to me, and I'd like to learn more about where to buy these lights. From what I've read on other threads, the T5 bulbs seem to be the gold standard. But the last time I was at my local hardware store they didn't have much to choose from - mostly just the standard 48" shop lights. So I guess I'm wondering where a person can buy these HO T5 bulbs (especially in a smaller size).

[Paul]

I've never seen 45Wcfls though I have seen and made use of the 42W cfls. Even those are not terribly easy to find.

[tropterrarium]

A few random points:
- source: go on-line with aquarium suppliers. Your hardware store will not have what you want. I made good experiences with MarineDepot.
- Type of bulb in terms of color. Aquarium lighting is geared to corals, which need a lot of UV. Stay away from UV. Us full spectrum, or plant bulbs (in the 5000-6000 Kelvin range). I use Giesemann Polychromes T5HOs.
- Light will produce heat, which will go into your tank. This can be desirable, or undesirable. If you are already living in a warm environment, possibly do not use a hood, but look for rim mounted or hanging fixture.
- Consider LED lights. They are new, but coming, and have lower heat output.
- As your lights are on a on/off schedule, no dawn/dusk with electrical lights generally speaking [there are some options here, but rather esoteric], you can roughly 1/2 the usually recommended (outdoor/natural light) requirements (in footcandles) with artificial light sources.
- It takes a lot of light for bright orchid light in a terrarium. As a first approximation, consider covering most of the surface on top with T5 bulbs. Then make fine adjustments with distance of bulbs from top, duration of light cycle, possibly turn some lights off during part of the day (simulating early morning, late afternoon).

Lighting takes some tinkering.

[Paul Mc]

WOW - thank you tropterrium. I did not know about the full spectrum and kelvin range. That was very useful indeed!

[Paul Mc]

PetSmart actually has a light stand that you attach a clamp light to. You slide it's base under the terrarium and then adjust the height of the light to where you want it. I would love to have this to keep the light a further distance from the terrarium to help reduce overall heat. I am going for a cool/intermediate environment with max light for phal's down to about 500 fc's.

I will check out some more places to see what I find.

[Ray]

Trop is right about the color temperature. Chlorophyll absorbs slightly more blue than red, and a color temp of roughly 6400°K matches it.

OK, time for a commercial: Hydrofarm carries a lot of different T5 fixtures and bulbs, but they will only sell to retailers, not individuals. Unlike most of their resellers, I discount their suggested retail prices, so if you see something on their website that interests you, let me know and I'll get you a price.

[tropterrarium]

Originally Posted by Paul Mc

WOW - thank you tropterrium. I did not know about the full spectrum and kelvin range. That was very useful indeed!

The term Kelvin refers to the color temperature of light. Incandescent light bulbs are around 2400 K, Halogen around 3200 K, daylight is around 5000-6000 K, UV has >10,000 K rating. So low Kelvin values = reddish light, high Kelvin numbers = blueish light. Plants like daylight so in the 5000-6000 range.

If you look at a light spectrum, from 400 - 700 nm (= nanometers = wavelength), then natural daylight forms a nice curve. Fluorescent tubes have more of a New York Skyline profile. Full spectrum lights are less New York and more like natural daylight. Hope that makes sense.

[Paul Mc]

Indeed it does - and it shows me just how ignorant I am about light, lol... Oh well, I'm learning!

[Ray]

I have more detail on color temp and appearance on my "Free Info" page, including a Java applet that shows the spectrum of each temperature, and what the "white" light coming from it would look like.

Light Sources & Color Temperature

[tropterrarium]

Hi Ray,

nice site and showing the different curves. The curves are the idealized spectral emissions (aka, black body radiation curves). But fluorescent tubes do NOT have such a nice curve. For an actual spectrum of a fairly good fluorescent tube, see e.g., Giesemann Lichttechnik - for the Giesemann powerchrome midday (which is what I use).
A cool white fluorescent tube has an even more ragged "curve" / NYC skyline.

So color temperature is one thing, the actual spectrum a very different one.

See wikipedia Fluorescent lamp - Wikipedia, the free encyclopedia bottom of page for comparison of a "typical" lamp (top) and a more full spectrum "natural sunshine" (middle).

To assess match of light source to natural light, there is the Color Rendition Index (CRI). The Giesemann has a CRI of 93. Some metal halides are a bit better (CRI of 96), I think cool white is around 50 or 60, so pretty poor. Some non-HO fluorescent lamps go up to CRI of 98 (have one in my slide viewer transilluminator), but at those high numbers, the reflector also plays an important role. so it is more of system value, than a pure tube number.