Equipment Review and Discussion :: UVB bulb science question

[scriabin]

Does anyone know what it is exactly about the "reptile" UVB bulbs that makes them different from standard fluorescents? I understand they put out a specific wavelength, but what is it about the bulb specifically that creates that wavelength whereas other fluorescents don't?

The reason I ask is, I've been putting together a pair of brackish aquariums (for a mudskipper and a puffer) and I wanted to use sand as substrate, so I shopped around for a while looking for sand that was safe for freshwater fish tanks, and after looking everywhere, I found a small fish store that sold 5 lb bags for $4 - that was much better than the petsmart price.

Then someone on a fish forum tipped me off to check out home depot, and lo and behold, they had the exact same sand, but sold it at 50 lbs for $3.50! I was amazed at the profit those "pet sand" distributors must be making, and on my way out of the store, I started eying their vast selection of florescent bulbs, wondering what it was exactly that made all of those reasonably priced bulbs, in all their permutations, different form the "reptile" bulbs that have been calibrated for just the right frequency.

It's probably just wishful thinking, but does anybody know the specific science and engineering that causes the reptile bulbs to emit the right wavelength?

Thanks,

Jonathan

[Arisu]

I was wondering the exact same thing in bed last night, HAHA. I'm going to revisit this thread to see if we have any luck with the answer!

[BullDog]

I hope someone can correct me if I'm wrong, but I think it has to do with the gases that fill the glass tube. UVB CFLs have different gases than standard household CFLs.

[scriabin]

I hope someone can correct me if I'm wrong, but I think it has to do with the gases that fill the glass tube. UVB CFLs have different gases than standard household CFLs.

If that's the case, does anyone know what the different gasses are?

[marisa]

UVB bulbs contain a special coating inside which allows them to produce UVB rays. Whether or not gas is produced, I don't know. I do know that if a CFL bulb is broken, the area needs to be ventilated, so something must be escaping.

[scriabin]

Do you know what the coating is

[TheComputerGremlin]

Here comes the scientist! Let me see if I can explain: Actually, I'm finding a distinct lack of information on this particular subject. But anyways, first, both your turtle bulb and the energy light bulb contain mercury, so please do not dispose of these in the normal trash. The energy bulbs have a coating to reduce UV output. Some UV does escape, there is a recent article saying that you could get a sunburn if you are within 12 inches of certain (defective) energy-saving bulbs for extensive times. However, it says maybe 1 in 5 bulbs are defective in this manner. All other bulbs won't emit a significant amount.

In short, regular fluorescents don't put off UV, at least not enough for your turtle to be happy.

[TheComputerGremlin]

It said it was a type of phosphor.

[marisa]

Yes, it is a phosphor. Eye problems associated with some of the CFL UVB bulbs are thought to be partly due to the phosphors that were being used in them.

[Fuzzy Hamster]

scriabin, I wondered the same thing about finding cheaper alternatives for lighting when I discovered other items that could be purchased much cheaper through a little research (such as 25 lbs of 'river rocks' for $6 at Lowes).

Unfortunately the same does not seem to apply to lighting. You may find the info at this web site interesting to read through;

http://www.anapsid.org/uvtable.html

Keep in mind that the recomendations in section 3 are based on reptile requirements rather than turtle reqs, but otherwise it is still a good read. There are also some additional links provided at the bottom that are interesting reads as well.

[Fuzzy Hamster]

So after a little more reading I found the following site ( http://www.reptilesdownunder.com/reptil ... losure/uv/ ) with some more interesting info.

In particular I found it interesting how similar the output of a GE CoolWhite bulb is to the output of a Hagen Repti-Glo, here: http://www.reptilesdownunder.com/reptil ... v/uvBoston

I'm no expert when it comes to lighting, and I'm not looking to make Spike a guinea-pig, but the info shown sures makes you wonder what we are paying for....

Its possible, or even likely, that some types of regular fluorescent bulbs do produce UVB, but manufacturers do not want to advertise it do to the link between UVB and skin cancer in people, as well as the potential for eye damage. There would not be any real danger though in normal household use, since most bulbs go into fixtures that diffuse the light anyways, and they would usually be far enough away (on the ceiling) so as to have little or no effect on eyes or skin.

[steve]

Regular compact fluorescents and halogens can produce some measurable amount of UVB (I have my own meter). However, at a distance of 12", the output is nearly negligible, though there are some high-powered halogens that emit extremely high levels of UV and need protective barriers. Results are questionable when you factor variables such as distance, burn/decay rates and wavelength. It's definitely a curious area of reptile keeping and one that should be scrutinized. Considering Zoo Med had their own significant problems recently, one can hope the money they spend on their products is for research and not solely on their marketing.

[scriabin]

where did you get the meter?

[imderanged]

I'm curious why they don't make a small bulb that emmits heat and UVB ...like the mercury vapor bulbs, but appropreate for a smaller enclosure?

[steve]

I got my meter at Carolina Pet Supply (it's the Solarmeter 6.2) and they seem to have a good deal on it now... http://www.carolinapetsupply.com/catalo ... cts_id=240

And imderanged has an interesting idea. I have a small halogen desk lamp and it has a separate glass UV filter. Smaller sized MVBs would definitely be popular, though I can see them accidentally being misused.