Re: Hagen Night Glo bulbs - truly OK to use?

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Posted by chris_harper2 on April 19, 2003 at 08:10:14:

In Reply to: Hagen Night Glo bulbs - truly OK to use? posted by Zeb on April 18, 2003 at 23:46:47:

Hi Zeb,

::I use Hagen Night Glo bulbs on both my water dragon and day gecko enclosures.....I like the looks, I guess.

I like the looks of red or blue night-bulbs as well. I like to get up in the middle of the night and check on my herps once in a while and I enjoy seeing what they are doing or where they have holed up for the night etc. This holds true for both my nocturnal and diurnal specimens.

::Now, I never truly understood the red bulb concept...

You're not alone, it's a confusing subject with a lot of misconceptions.

::I recall reading that most reptiles could see it, but it was so subdued it didn't keep them away...same with the blue bulbs.

This is basically true - most species actually need some visible light at night.

In a nutshell, it would likely be stressful to a nocturnal OR diurnal species of reptile to be kept in complete darkness at night. Same holds true for humans. However, keeping them lit 24 hours a day also causes stress. So the question is what spectra and intensity of light becomes stressful to different species at night? We know it lies somewhere in between complete darkness and full light, but where is very difficult to measure.

First, let me explain that true darkness or complete lack of visible light is something that rarely occurs in nature. Some caves have a complete lack of light, but I can't think of any reptiles that occupy those habitats. Some blind salamanders but no reptiles.

Sea Turtles probably dive beyond the range of visible light and I image some aquatic reptiles have under-water or mud burrows that filter out all visible light.

Even deep (non-aquatic) burrows often have some measurable visible light.

So of course reptiles can see the light produced by red and blue bulbs, the question is 1)how much intensity of this light is visible to them? and 2) at what point does it become stressful to different species? This is what we do not know exactly.

Unfortunately this is not only a species-specific question, but likely also has population and individual variation as well.

So without getting too specific, near-complete darkness (like what you might find in a basement with no window, or a closet with a towel shoved under the door) likely would be more stressful to herps than providing too much visible light during the night.

::I've also heard from other herpers that the blue bulbs heat less.

I doubt this is exclusively true, but I had a 25 watt blue bulb from one manufacturer that was cooler than a 25 watt red from another. I suspect this had more to do with manufacturing tolerances than anything special about the blue vs. red coating.

::What is correct? Can they see red? Blue bulbs?
::Is it OK to use?

In summary, the reptiles can see them - they are supposed to - but it is unlikely that the light provides too much visible intensity for them. Especially for the diurnal species you keep.

I hope this made some sense. I tried to avoid being technical but I'm still groggy this morning and may not have done a good job of writing in simple terms.

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Thanks.... Zeb 04/19/03 (0)