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Thread: Light for Nepenthes

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    nimbulan's Avatar
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    It shouldn't matter unless you can't physically fit enough T8's into a space to provide the required light level. For the same amount of light, you will get the same amount of heat no matter which type of bulb you use. People often equate T5 bulbs feeling hot to the touch with them producing more heat, but it's simply a side-effect of the bulbs being more powerful. A general rule is 2x T8 = 1x T5HO, both for light output and heat output.

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    Quote Originally Posted by naoki View Post
    What is this based on? Electric power get converted to light or heat. So higher efficiency light gives more light and less heat than lower efficiency light. If you are talking about T5 normal output, then it has higher efficiency, so you are correct. But if you are talking about T5HO (high output), then the efficiency is pretty similar to T8. In lower temp, T8 has slightly higher efficiency than T5HO in general, and T5HO is slightly higher in warmer temp. So if you compare 1 bulb of T5HO vs 2 bulbs of T8 (to make the amount of light similar to each other), the heat production is similar. Now, there are some ballast related efficiency. Some cheap T8 fixtures may be using cheap, less efficient ballasts.

    This is the story when you have some enclosure to capture the heat. In a wide open room, this will not raise a lot of temperature (unless you have lots of them). But if you limit the heat radiated toward the plants from the light bulbs, we feel T5HO might give a bit more "dense" heat. But if you adjust the amount of light (density), it should be similar since the emission spectra is similar between typical T8 an T5HO.
    I read this somewhere online, so it may or may not be true. The lights I'm looking at are T5HO - I forgot that they were high-output.
    When you say 'limit the heat radiated towards the plants', are you referring to using a reflector/reflective material?

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    I'm in the same zone as you and kept my Amps and Bical in a 20G low covered aquarium on a window sill in my bathroom. All the plants pitchered and were healthy. Now I keep them in a greenhouse, but the aquarium worked well. If it looked too wet, I would just crack the lid for a few days.

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    Quote Originally Posted by Bluemoon99 View Post
    I read this somewhere online, so it may or may not be true. The lights I'm looking at are T5HO - I forgot that they were high-output.
    When you say 'limit the heat radiated towards the plants', are you referring to using a reflector/reflective material?
    It doesn't have to be related to the reflector. Some portion of the energy in electricity gets converted to the light, and the rest of energy is "wasted" as heat. This loss could occur in the ballast or in the tubes. Then the heat get dispersed by conduction (e.g. from inside of ballast to the metal surface of the fixture), convection (from heated metal fixture or light bulb to the surrounding air), or radiation (emitted as electromagnetic wave like Infrared light). When I said "limit", I was talking about the radiation part, not convection part.

    When you put the hand close to the light, you can feel the heat. Basically, in some light, heat is emitted (e.g. as infra-red light). To be honest, I don't completely understand why IR becomes heat even though blue photons have more energy (maybe someone can explain it?). People say that HPS throws a lot of heat, and this is the reason. Here is an example of HPS emission, and you notice a peak between 800-850nm: http://customledsystems.com/wp-conte...wavelength.png Fluorescent light doesn't have lots of IR, but it does emit some heat. So the amount of heat "thrown" toward plants depends on the emission spectra. Since the emission spectra aren't so different between T5HO and T8, this part shouldn't be so different.

    Sorry this is too much details, and probably derailing the discussion. I'm basically saying the same thing as nimbulan who stated it in a much simpler way!
    Last edited by naoki; 09-22-2016 at 11:52 AM.

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