Terrarium lighting 101

[skylsdale]

Just wanted to comment on the kelvin issue. Coming from the reefkeeping hobby, color spectrum/kelvin and PAR is a heavily debated issue when dealing with coral growth and the photosynthetic needs of their zooxanthalae (symbiotic algae that gives the coral its color).

Anyway, for the greatest PAR and best coral growth, 6700k halides are used because this really close to the spectrum of the noonday sun over the tropics(which is a pretty commonly accepted in reefkeeping.) I notice that you suggest 5500k for this...a kelvin rating that any serious coral keeper would avoid like the plague. You also describe the 6700k spectrum as "blue". Ironically, the reason so many reef hobbyists don't like this bulb (regardless of it's ability to stimulate coral growth) is its yellow cast on the tank. Most people prefer a 10,000k bulb for a nice clean white...and don't see much blue until they hit a 20,000k bulb. However, it should be noted that the lighting industry uses kelvin ratings somewhat loosely and more for the benefit of the hobbyist so that we can have an idea of the spectrum it will create (i.e. 50,000k bulbs, etc.)

[D muscipula]

Skylsdale, the thing you are forgetting is that the water column absorbs a large amount of light, mostly of the longer wavelengths (red). *That's why deepwater corals use more actinics (blue, high K) than shallow reef corals. *Continuing the progression, a terrestrial plant will actually see a lower K color temperature than the reef corals. *FW tanks are also commonly lit with lower K bulbs than a reefkeeper might use, because the plants often grow barely submerged at all.

I have to disagree with some of the statements in the original post, too. *My CPs are currently under 3500K lights because that's all HD had when i bought them, and i haven't bothered to pick up others yet. *The plants are growing well. *I have noticed that some seem to feel "underlit" while others are growing and coloring nicely, which just seems to strengthen the suspicions i have that actual PAR spectrum and useable light is very plant dependent.

One thing that was left out so far is that there are essentially two types of linear fluorescents commonly in use: the old T12 and the preferred (efficient) replacement, the T8. *This is quite important to people setting up new grow areas, because the market and availability is changing (relatively) rapidly right now, and some vastly superior options may be missed if this isn't understood when buying. I've already written a volume about this (LOL) based on my rather extensive online research to the listserv, but if anybody missed it and wants to read, i put it up as the beginning of a FAQ a la Krib here. *Which reminds me, the Krib, one of the first and best aquarium hobbiest web sites, has a lot of information on lighting.

Cheers

[wruiz29]

confused out of my mind... I just bought a 5.5 gallon fish tank (15" by 7" ground area) that I am going to convert to a terrarium for about 14 vfts, what kind of lighting would be best and how far? I've been reading this thread, and there are so many bulbs and lumens and who-knows-what that I have no clue what to buy, I'd appreciate any help. -William

[joseph]

No prob we just ask that you read it. To start with the lights should be as close as possible. What type of top do you have for the tank?

I think in your case you have two basic choices, 1st, find a lizard style terrarium lid that has two standard bulb sockets and fill them with compact florescent bulbs (cool whites). Second choice, cover the top of the tank with a piece of plexi glass and on top of that lay 3 or 4 18 inch florescent tube lights (cool whites). These are available from walmart as under counter mounted light strips.

Either of these two choices will be good, unfortuanatly lighting is one of the highest investments in this hobby.

Almost forgot the third choice, a ledge by a sunny window. Be very careful to balance the amount of light against the temperature. If the tank gets too warm use a shade cloth or anything similar to limit the sunlight but keep it bright.

good luck
joe

[wruiz29]

thx joe, I currently have two philips "Agro-Lite's" 60W each, and one Philips "Daylight" bulb 15W 750 lumens , and these three bulbs are screw ons in clamps, so they are not touching the terrarium, the bulbs are about 6 inches from the glass. Are the two plant lights and the one daylight bulb sufficient? too much? -William

[joseph]

Not familiar with the lights your using but I recognize the clamps. For that setup you should be using the compact florescents, largest you can get, like 25 watts. Ditch the incadescent grow lights, too much heat too little light. Put the florescents right against the glass. Remember to buy ones that say cool white or full spectrum. The full spectrums are still hard to come across, perhaps you can find one at home depot.

Hope this helps
joe

[wruiz29]

thx once again, I will go return the bulbs I got, and go for the compact fluro.'s in cool white, also how long should I expose my vft's to these lights each day? how many hours? -William

[joseph]

hmm...The lights are cheap to run so I'd say go for 16 hours as long as it is dark in the room the other 8 hours.

joe

[wruiz29]

would your recommend a 25 watt compact fluroscent daylight, cool white, or full spectrum?

[joseph]

full spectrum prefered. Then daylight.

joe