About Us
Contact Us



Sign up today for our fortnightly FREE "Keeping Reptiles" Newsletter.

  • Jam-packed with ideas and tips
  • Stories and information on keeping reptiles.
  • Ideas for cages
  • Keep informed and learn about reptile keeping.
  • Web-sites and places of interest.

Sign up now and I'll send you a bonus FREE gift of "15 Top Snake Keeping Tips"
(Value of $16.95)

First Name:

Last Name:

E-mail Address:



I am ... very happy with your plans, the organization that you have put into it and I am extremely happy with the response I have gotten from you when I have encountered a problem.
It sure does save money. At the same time it allows me and others like me to experience making the cage for our animal (animals) that we care so much about. I think that when someone takes the time to sit down and make something like this for their animal it really shows how much they care for them and respect them.

With your plans you can also alter the cage to each and everyone's specifications, or needs. I think what you are doing is wonderful and I want to thank you again.

Robert Hansford


"This is going to make an 11 year old and his lizard Rex very happy".


Spent $108.00 at Lowes, another $65.00 at Home Depot buying things that Lowes didn't have..... Spending time with my son in a hardware store.... PRICELESS!"


"Overall, the best thing I have found from the cage designs... is that:
They work!!!!

They allow you to view and touch your Iguana from all sides, This is a must!

Once you have the material list you don't go back to the hardware store.

Just follow the instructions and it comes out perfect.

Your maintenance will be much easier.

Your iguana will thank you

Once again, you will have built something cool. "

Regards and best to all our Green Iguana friends, Lance and Joey Portwood Glidden, Texas ".


"Very well thought-out designs"



UV-lamps for Terrariums and their effectiveness

by Michelle T. Nash

Here's a subject that's near and dear to my heart. I've been wondering about this for a long time. Recently, the Chicago Herpetological Society reprinted a translated version of a research article from Finland. I have taken the liberty of copying the Title, Author and Abstract as seen in the CHS Bulletin, followed by my own personal synopsis of the article, with a few quotes from the article sprinkled here and there. I hope everyone finds this helpful.

SOURCE: Bulletin of the Chicago Herpetological Society Volume 40, No.1 January 2005

Original paper "UV-lamps for Terrariums: Their Spectral Characteristics and Efficiency in Promoting Vitamin D3 Synthesis by UVB Irradiation" by: Jukka Lindgren may be downloaded from this website

Translated by: Tiina Siitonen, Jukka Lindgren, Barry Brown


Sufficient irradiation within a narrow sub-band of the UVB range is a prerequisite for the photosynthesis of vitamin D3 in skin. Although radiation below wavelength of 300 nm (nanometers) promotes photosynthesis of vitamin D3, radiation above 300 nm destroys vitamin D3 that has been already synthesized in skin tissue or nutritionally obtained. Furthermore, skin temperature has a significant effect on the pace of vitamin D3 syntheses. In a terrarium, the required UVB-radiation has to be artificially produced with dedicated lamps.

In the study, the characteristics of light produced by fourteen different models of UV and full spectrum lamps specifically designed for terrarium use were measured over a range of 250-800 nm. As a reference, the spectrum of natural sunlight was also measured when the sun was at its highest point of elevation in the southern sky of Finland. The proportion of radiation energy that takes part in the photosynthesis of vitamin D3 was determined and the D3 Yield Index was calculated. Significant differences as large as a thousandfold were found in the D3 Yield Indices. The resulting conclusion is that UVB radiation as a percent of the total radiation figure does not necessarily give a true indication of a lamp's capability to maintain cutaneous [(in the skin)] production of vitamin D3.


As stated above, only a certain range of wavelength of UVB rays promotes vitamin D3: (295 -300nm)

The next range up the scale actually is known to destroy Vitamin D3: (315-330nm)

The UVB percentage on packages should not be the sole basis for determining it's ability to promote D3 synthesis in your reptile.

It's the amount of the beneficial wavelength weighed against the amount of D3-destroying wavelength that's a better measurement to consider. And of course the packages don't include this info.

Some UV lights are not meant to promote D3 production, but to merely provide a broad spectrum of light to more closely mimic the wide range of UV found in sunlight outdoors.

Heat helps the skin make Vitamin D3. Eight times more D3 can be synthesized at 25*C (77*F) than at 5*C (41*F)

Here's a quote from the article: "It should be noted that the theory and research discussed above relate to human skin. However, the chemistry of the skin of terrestrial vertebrates is similar enough to that of humans to justify the theory to be extrapolated to reptiles as well." FINALLY, HUMANS WERE USED AS GUINEA PIGS TO BENEFIT REPTILES Hee Hee Hee!

The UV measurements taken on the 14 various lamps was performed at a distance of 30cm (almost 12 inches).

The best lamp tested indicates a D3 photosynthesis rate that is ½ that of the natural sunlight on the summer solstice in Finland - Which we all know is nowhere near the equator - so that means it is not the most preferred UV comparison but as you can figure out, man can not replicate the full magnificence of the sun in these little light fixtures and we are simply trying to provide them with the next best thing. And on a side note, though this was not mentioned or hypothesized within the article, this makes me wonder if we should continue to offer some vitamin D3 supplementation even when providing the best light on the market. Please see the end of this long post to get a basic list of the "best" D3 promoting lights out there.

Note that the measurement of the sun is such that it is only a single measurement of the light encountered during the day and not what would be available throughout the entire day. It would be weaker in the morning and evening where the UVB lamps offer a consistent amount of UVB through the day. My conclusion based on this info is that although the lamps are weak compared to the sun they offer a constant supply of D3 producing light whereas the sun ebbs and flows throughout the day and the seasons so maybe our weak little human-made lights are sufficient.

For those interested in statistics, only one unit of each lamp was used in the testing. Though this is a very small sample of each product, it mimics the consumer's purchase of one lamp per cage so it makes the odds with consumer uses virtually equal.

The D3 yield index is a measurement of how well D3 would be synthesized under the influence of the wavelengths offered by each lamp.

It is interesting to note that they also tested the best lamp after 10 months of use (12 hours a day) to see what kind of reduction in effectiveness there would be. Happily, it is reported that there was a minimal drop in effectiveness. A drop of only about 16 percent was measured. Though I did some calculations based on Table 3 figures and noticed that the ratio of "good" to bad" wavelengths was improved slightly during the 10 months making the drop in "good" wavelengths less serious when it comes to producing & not destroying D3.

"...True-Light [brand] lamps are obviously NOT UV lamps, although their retailer has sometimes recommended them for this purpose." These are one of the lamps that are better for simply illuminating the enclosure.

"The lamp models Repti Glo, Life-Glo, Exo-Terra Repti Glo 2.0, and ESU Reptile Super UV Daylight, emit only a few percent of their radiation in the UVA range, with even less in the UVB range. Active UVHeat lamp also stands out with its rather low percentage of UVB radiation; this is however, a bit misleading, since the nominal power of this lamp is significantly higher than that of any other. Although its irradiance in UVB region is quite high, this is still not a proof of its high capability to promoting photosynthesis of vitamin D3 as shown later."

Not enough info was available for them to offer data on the effect of "D3 photodestruction" on the lamps that were tested, though they did have a separate table comparing the good to bad UVB amounts for the lamps. I found the ratio of good to bad UVB amounts for the Reptisun 5.0 UVB lamp was 2.057 to 8.232. This made the ratio of good to bad UVB rays about 1 to 4. This doesn't sound too good till you compare it with others whose ratios were ranging from 1:11 to 1:78 . The article stated more research is needed to resolve this.

It was interesting to note the mention of dangerous UV rays being emitted by the Active UVHeat lamp. (dangerous to animals and humans) It recommended offering a shaded area in the terrarium and suggested a single piece of "window glass" would adequately shield nearby humans from the harmful radiation. It didn't say if a terrarium or aquarium glass was the equivalent of a piece of "window glass".

Also of special note was that the measure of "total" UVB is not directly related to a lamp's ability to promote D3 production.

Again, it's the range of "good" UVB's offered that determines this.

"The Reptile Desert 7% UVB, manufactured by Energy Saver Unlimited (ESU), turned out to be a disappointment. Despite it's name, the unit only produces 0.3% UVB radiation and its D3 Yield Index is only 0.5 ." COMPARE THAT TO THE D3 YIELD INDEX OF THE REPTISUN 5.0 UVB LAMP MEASURING AT 439.3 !!!!!!! That's almost a difference of the Reptisun 5.0 being 900 times better than the Reptile Desert 7% UVB lamp.

This was an awesome article and I had been wishing for something like this to help me figure out which lamps were really going to help my lizards thrive.

"When evaluating the proportion of UVB radiation only, Zoo Med ReptiSun 5.0 and Sylvania Reptistar stand out. Over 6% of their total irradiance is in the UVB range. Narva Reptilight and R.C. Hagens Exo-Terra Repti Glo, models 5.0 and 8.0, make up another group with their 3-4% UVB proportion. The rest of the lamps produce only extremely small amounts of UVB."

Here's the list of lamps and their D3 Yield Index as shown in the article:


D3 yield index
Reptisun 5.0 UVB
Reptisun 5.0 UVB (used 10 months)
Exo-Terra Repti Glo 8.0
Active UVHeat
Exo-Terra Repti Glo 5.0
Repti Glo
ESU Reptile Super UV Daylight
Exo-Terra Repti Glo 2.0
ESU Reptile Desert 7% UVB
True-Light Daylight 6000
Sun(at summer solstice in S. Finland)

The D3 yield index column is what makes it easier for pro's and novices alike to determine which lamp is really helping the lizards make their own vitamin D3. Also on the market is the Reptisun 10.0 UVB lamp, which, according to a ZooMed/Reptisun representative I spoke with on April 2nd, is even more powerful than the 5.0 at the D3 producing range. He said his company has been testing and working to produce their UVB lamps in the CORRECT UVB range to promote photosynthesis of vitamin D3 in the reptiles. Hats off to them!


Michelle is an avid reptile keeper in the Chicagoland area. She stays involved in the Chicago Herpetological Society and has had writings published in the CHS Bulletin. She has done educational presentations for local grade schools and exhibited at North America's largest educational reptile show, ReptileFest, held in Chicago during April each year. She is a wife and mother and has been a nature enthusiast since the age of 7, when she spied her first coral snake in a pine forest of the southern U.S.



Find out "How to build enclosures for reptiles" . Full color pictures, detailed diagrams and easy to follow, step-by-step instructions.


Back to Articles