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Are compact / coil UVB bulbs still unsafe to use?

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CooperDragon

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I don't know that they're unsafe in that they emit short wavelengths which can be harmful (I can't say for sure without testing data however). The issue I have with them is the relatively narrow spread of UVB they emit. Think of an inverted lighter flame. A narrow cone that is intense at close range but doesn't put much out to the sides or at a distance. I prefer the tubes because they emit a much wider, more even beam which is easier for the dragons to bask under evenly (fit their entire body in an area with approximately the same UVB levels).
 

RelentlessChaos

Juvie Member
Original Poster
Yes, I agree.

Although, do the coil / compact bulb still pose a danger to a Bearded Dragons eyes or any other health concerns? When I search online, I find that this was also concern in the past, aside from the lack of spread.
 

CooperDragon

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They can be intense. Look into a compact fluorescent vs a fluorescent tube yourself and you can see the difference. I think a lot of that has to do with the distance and angle at which they're mounted. If they're at about 6'' above the basking spot directly overhead they may be fine (depending on the brand and manufacturing quality I suppose). Based on what I see on here most of the issues come from improper exposure to UVB leading to appetite issues and MBD.
 

Taterbug

BD.org Addict
They are not unsafe so much as unsuitable. They are fine (assuming you get a reputable, high quality brand) for lower light needs animals, small enclosure and the like - the faulty construction/design were reformulated years ago. Again, they are unsuitable though, so like any light (UV or heat) if positioned improperly (such as too close, poorly angles) they can cause health issues.

Fran Baines had a pretty good comment to this same conversation else where.
The compact fluorescent lamps, whether they are shaped like a coil (eg. ExoTerra 100 - 200 series) or as three bars looped at the top (eg. ZooMed Reptisun and Arcadia Compact Reptile series) are basically just T5-HO fluorescent tubes that have been bent up into a small space, and had a miniature ballast installed in their white plastic base.
So whether they can emit UVC, UVB, UVA and visible light depends, just like all fluorescent tubes, upon the type of glass used, and the phosphor (white powder coating the inside of the glass).
The best quality brands use a borosilicate glass which blocks all UVC and very-short-wavelength UVB, but lets through UVB from 295nm upwards to 320nm, and also all UVA and visible light.

The mercury vapour inside a fluorescent tube, when the lamp is switched on, creates a brilliant arc (like a long thin spark) right down the tube, that emits UVC, UVB, UVA, visible light and a little heat.
The white phosphor coating absorbs the UVC and converts it into more UVB, UVA and visible light.
Any UVC and very-short-wavelength UVB can't get out of the tube into the room, because the glass absorbs it. The glass lets the rest through, so the lamp "emits" UVB from 295nm upwards, UVA, visible light and a little warmth.

Problems usually only occur with very cheaply-made Chinese bulbs and tubes which are made from a quartz glass, and quite possibly, also cheaper phosphor powders. Quartz glass doesn't block short wavelengths - it lets UVC through. (It's what UVC-emitting fluorescent tubes for sterilising water are made out of.) The quartz glass tubes are not always perfectly smooth on the inside; the quartz creates tiny threads like microscopic spikes along the length of the tubes. The phosphor, when it's added (either by dipping or blowing) doesn't stick to these threads. You can see this when you look at a very cheaply-made tube, before it is switched on - you'll see hairlike clear streaks in the white surface. These are tiny gaps where there is no phosphor to catch the UVC. The result is a tube that can "leak" UVC through the tiny clear streaks, when it is switched on. The leaks are very, very small, so the UVC can only be detected at close range. But hey... why risk subjecting your poor reptile to any UVC at all, when better, safer products are available?
Sometimes the phosphor is very thin, too. And sometimes (rarely, nowadays, but I still see one or two sent to me as prototypes) the phosphor they use actually produces very-short-wavelength UVB. These tubes are even worse, and could cause eye and skin problems quite easily if the reptile gets close.

Cooper, you may be thinking of the beam pattern of a MVB? On their own coil bulbs have a largely round beam, metallic reflectors can add 'punch' to them but they don't have the flame shape on their own or in a white painted dome. http://www.uvguide.co.uk/phototherapyphosphor-tests.htm#reflectors They do have pretty steep gradient especially at the distance to achieve dragon basking levels.
 

CooperDragon

BD.org Sicko
Staff member
Moderator
Taterbug, you're right. I was mistaken. I'll have to run back through my notes and find the bulb/fixture combo that was producing the narrow, intense beam I was thinking of. It all starts to blur together after a while :oops:
 

RelentlessChaos

Juvie Member
Original Poster
I've used the Reptisun 10.0 fluorescent tube since the day I discovered this site and I've disregarded compact / coil for a few reasons which we've somewhat discussed already. Although, I've never taken MVB into consideration. How are they when comparing with the Reptisun 10.0 fluorescent tube?

I've read that MVB are better than coil / compact but that they still have pros and cons. For example, one side of the tank still does not receive UVB. And maintaining the proper UVB distance as well as heat temperatures can be tough since it's a 2 in 1 bulb. For pros, obviously it limits the need for many fixtures and bulbs and well, it's "2 in 1".

Anything else about MVB I should know?

I'm curious since my current setup could benefit from something like a "2 in 1" MVB. Assuming that the UVB output is good.
 

Taterbug

BD.org Addict
Just like tubes some brands are good some are junk. I don't use them for the reasons you list, I prefer to control my UV and heat separately and a tube works best as far as coverage goes for my large cage (areas of No UV are a good thing though. A gradient just light heat is best). UV output from the good MVB is high though, so could be paired with a low output tube (T8) for a "sunny" spot for example. I think they also tend to have a purple or green cast to the light, from what I have read.
 
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