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UVB Results Compared Through Screening

Discussion in 'Habitat Lighting' started by DragonsKeepers, Jun 12, 2012.

  1. DragonsKeepers

    DragonsKeepers Subscribed User Premium Member

    I ran this test using the bulb I have for my beardies. I will be running this test again with the Powersun 100w bulb I have as well.

    48" Arcadia 12% HO bulb:
    No screen: 6 inches 340; 12 inches 180
    Window screen against bulb: 6 inches 218; 12 inches 113
    1/8" screen against bulb: 6 inches 280; 12 inches 141
    1/4" screen against bulb: 6 inches 337; 12 inches 178

    Based off this data the following is allowed percentage through each type:
    At 6 inches to basking spot:
    No screen: 100%
    Window screening: 64.12% (Blocked 35.88%)
    1/8" Reptile screen: 82.35% (Blocked 17.65%)
    1/4" Reptile screen: 99.12% (Blocked 0.88%)

    At 12 inches to basking spot:
    (This is relative to 12" measurement only (not compared to 6")
    No screen: 100%
    Window screening: 62.78% (Blocked 37.22%)
    1/8" Reptile screen: 78.33% (Blocked 21.67%)
    1/4" Reptile screen: 98.89% (Blocked 1.11%)

    I hope this helps people when deciding what kind (if any) of screening to choose for their reptile tops. I also found when looking at different bulbs (including the Powersun, Zilla Desert 10.0, and ZooMed Reptisun 10.0), that the Arcadia provides the closest to real sun UVB levels. I know that you can't directly compare the numbers from the Solarmeter 6.2, but they have substantially higher output of UVB levels read by the meter. I would suggest anyone looking into new bulbs, check out and talk to Todd. Their fixture also includes a nice reflector built in to it. I got my tester and light from there at better prices than anywhere else. Again, that's the bulb and fixture I used for this test.
  2. Beardiebro

    Beardiebro Active Member

    Where do you get arcadia bulbs? Thanks so much for this info.
  3. DragonsKeepers

    DragonsKeepers Subscribed User Premium Member

    The site is a little weird as far as formatting, but search for 12% lights for bearded dragons and your size. They're a little more expense, but worth it for the quality and superiority I've seen. It also illuminates better so it keeps the whole enclosure lit up better.
  4. justor

    justor Elite Member

    This is great! Thanks for the help.

    The results are more or less what I expected. Although I thought the window screen would block more than it did.
  5. Vers

    Vers Elite Member

    Nice--thanks for the test. I just ordered and installed an t5 HO fixture with an Arcadia HO 12% bulb in my new enclosure, which was also ordered through I currently do not have a UV meter but given the test materials delivered with the bulbs it appears as though they will perform well enough.
  6. DwarvenChef

    DwarvenChef Elite Member

    First off thanks for the test results :) I'm all for making this a sticky :)

    Looking at their sight they list bulbs in percents 12% and 6%. I'm assuming this can be related to the mass markets 12%=10.0 or 6%=5.0 as far as what the needs are per herp kept?

    I'm looking to put in a single tube fixture over all 3 tanks that I'm setting up for my Emeralds. Right now I have the 3 coil types in the 5.0 range and I want to go a single bulb for the remodle. Am I correct in thinking that the 6% bulb is what I need and getting the basking point up to the 6" lvl ?

    Also what would the heat output be of that type of bulb? Or would it be best to start another thread...
  7. justor

    justor Elite Member

    I agree, this would make a great sticky. Probably should be moved to the lighting section though.
  8. DragonsKeepers

    DragonsKeepers Subscribed User Premium Member

    The 6% is the 5.0 high output. The 12% is the 10.0 high output. As far as the coil bulbs, they are horrible after any distance. I have a 5.0 coil and the reading dropped to 0 after about 8-9 inches if I recall. I wish there was an easy way to compare between bulbs though because even my MVB only reads in the double digits. If anyone knows how to compare brand to brand, I would be willing to do a full type-up of my findings of a number of different bulbs I have.
  9. DragonsKeepers

    DragonsKeepers Subscribed User Premium Member

    Sorry, you're right - I forgot there's a lighting section - my bad!
  10. mld

    mld Subscribed User Premium Member

    Thanks for doing this test! Obviously no screen is best and if you do 1/4" hardware cloth is better than the screen top.

    Also I would love to know what is a good level for a bearded dragon?
  11. DragonsKeepers

    DragonsKeepers Subscribed User Premium Member

    I will do some outside comparisons for different points in the day in the sun and shade. Right now there is a wildfire smoking out the state, but as soon as it's calmed down, I'll do those measurements. I think that would be as close as possible to figuring out what a bearded dragon would actually be getting in the wild. I know my beardies will move around a bit, but they really like their UVB spot up on their ramps (about three inches from the light).
  12. SpidaFly

    SpidaFly Elite Member

    There's still some voodoo going on here - though I'm at least glad to see the community challenging the tired "5.0 is for forest lizards, 10.0 is for desert lizards" marketing paradigm. This was the entire point behind the project at UV Guide UK - Ultraviolet Light for Reptiles - UVB reptile lighting on test - sadly that project seems dormant.

    While I suppose one could say that the Arcadia 6% is somehow analogous to the ZooMed 5.0 and likewise with the 12%/10.0, this is not strictly accurate and leads to a further misunderstanding of what these numbers actually mean and how light actually works.

    So what DO these numbers mean? I'll use my favorite bulb, ZooMed's 10.0 for an example: the "10.0" is ZooMed marketing labeling that is intended to indicate that 10% of the electromagnetic energy emitted by that bulb falls within the UVB spectrum. Their website also claims "30% UVA" - this is intended to indicate that 30% of the electromagnetic energy emitted by the bulb falls in the UVA spectrum (this is significant because some of the UVA spectrum is visible to to reptiles). Presumably the remaining 60% of the electromagnetic radiation generated by the bulb falls in the "visible light" spectrum.

    So does this mean that a 12% is somehow "more powerful" than a 10.0, and 10.0 "more powerful" than a 6%, and then a 5.0, and then a 2.0?, etc etc? Well, yes and no. Assuming that a 12% and 5.0 with comparable wattages are being considered at equal distances and similar mounting conditions then yes - the 12% is "more powerful" - or perhaps we should say that the electromagnetic radiation being generated at fixed distances is of greater intensity (uW/cm^2 in the case of the Solarmeter 6.2).

    But what if you test a "5.0" up close and a "12%" far away? Given that the intensity of our radiation falls off quadratically, clearly you could easily find near distances from a "5.0" that would yield a higher intensity than a far distance from the "12%".

    What if you line the top of your enclosure with 10x "10.0" bulbs (ahem... thought experiment only, I'm not suggesting that this should be done)? Well by virtue of increasing the overall wattage of the radiation you're generating, you're going to have very high UVB intensity. You're also going to have very high UVA and visible spectrum intensity. But guess what? The light coming down from the top of your enclosure is STILL "10%" UVB! It's still 30% UVA! All the redundancy accomplishes is raising the wattage of radiation you are generating and sending toward your lizards skin and eyes!

    The point of this part of my rant is to indicate that 12%, 10.0, 6%, 5.0, 2.0, etc... are NOT indicators of POWER, they're simply describing the type of spectrum being generated by your tube!

    So... 5.0 isn't for forest lizards, 10.0 isn't for desert lizards... what is the meaning of this???
    I started doing heavy research (and money) into the mathematics behind how this stuff works after having the following conversation with my excellent herp vet:

    Vet: <insert long winded lecture frequently citing papers where D3 blood levels were checked after periods of exposure to UVB sources>
    Me: So wait... if what you're saying is true, why don't I just let me lizard get within 8" of two 10.0s?
    Vet: Right! Why don't you?

    Wow. Well after spending so much time researching forums such a this one, RFUK, and others who constantly reinforced the line that "5.0 is for forest lizards, 10.0 is for desert lizards"... well I had a bit of a cognitive crisis! How could both the vet AND the community be right? Well, one or the other had to go so I started doing my own research (with the kind assistance of my vet's access to veterinary journals on the subject... :-")

    Well, after all the research, what have I come up with? My Australian water dragon is offered several comfortable resting areas (I'm not going to use the term "basking", I'll explain that in a moment):
    - His low points have almost no UVB Water level/soil level/cooler areas of the enclosure have no UVB.
    - Mid point basking shelf enjoys ~30 uW/cm^2. That's a fairly low number, but probably causes at least a little effective D3 synthesis.
    - High point is a gentle climb (read: a gentle UVB gradient which allows the reptile to self select an intensity between 30 and the maximum) up to a point 7" from an unreflected T8 fixture that contains TWO ZooMed 10.0s.

    TWO ZOOMED 10.0s within 7" of your FOREST dwelling WATER DRAGON? :eek::eek::eek: ZOINKS man you're going to fry your dragon!
    Not so fast! He has showed absolutely no indications of Photokeratitis or darkened skin, and he also shows absolutely no evidence of metabolic bone disease! He lounges READILY at this high point where he is able to access a UVB intensity of ~85 uW/cm^2 (per my Solarmeter 6.2).

    Take a look... does this look like a fried dragon with eye problems?
    "Garson, that'll be a cup of morio larva in a generous calcium sauce, and a glass of your finest fluval filtered water, please! Yes of course that will be room service!"

    Want to know something EVEN BETTER? Before I put that climb in, he really only had access to a maximum of ~30uW/cm^2. He spent nearly ALL of his time during those few weeks up on that shelf. Since I put that climb in he has been significantly more active - spending significant time there since he's clearly comfortable, but also resting in the shade of the branch on his shelf, spending time in a nice cool spot by his water, and returning to his hot spot after a bath, then back to the top of the rotation... ;) What an incredible creature - when offered so many different gradients, he knows just how to select what he needs when he needs it!

    Now, as with anything there's a caveat. Since I was a child I have personally only have dealt with iguanas and agamids. Apparently there ARE issues keeping chameleons and nocturnal/crepuscular geckos under high radiation setups. I don't personally know anything about this. Perhaps there's someone out there who has done proper research with these animals. I know I'll be doing the research when I get a gecko, but for now my understanding is focused on agamids and iguanas.

    So how much does my lizard need?
    Well, that's a hard question for us humans to answer unless we have access to scientific journals, ability to draw our lizards' blood to test D3 levels etc. So what CAN we do?

    Well, for hardier-skinned diurnal basking species (agamidae, iguanidae, etc.) the answer is: ask your lizard! We obviously all love our reptiles and watch behaviors, so... offer a gradient and determine what it likes! As I mentioned earlier, I offer my water dragon up to 85 uW/cm^2. Do I consider this enough? Yes. Why? Because he moves around, moves into shade, and sits in zero UVB areas as well. Am I going to offer more? Yes - I plan to finagle my setup into offering 100+ uW/cm^2. I'm not in a super hurry to do this however, as I'm sure that I'm not doing my dragon any harm at all with my current UVB setup and other care priorities.

    As DragonsKeepers noted, beardies are certainly little sun worshippers and will lounge in very high intensities. My beardie isn't getting "sun worshipper" level UVB at this point, but I aim to be offering him at least 150uW/cm^2 when I rework his enclosure.

    Can we go overboard?
    Absolutely we can. Just like us, our lizards can develop Photokeratitis. You can avoid this by avoiding long term exposure to very high UV radiation. But what is "very high"? Consider Phoenix AZ at high noon. Most people with healthy eyes can walk around outside with no trouble. Guess who else can operate under these conditions? Diurnal basking reptiles! Admittedly they typically will seek shade after warming up, so they do indeed try to avoid extremely intense UV intensities.

    So what is "extremely intense"? Well right now it is 13:33 and I've got a completely cloudless sky. I read 389 uW/cm^2 for UVB in direct sun, and in the low 30s due to scatter etc. under the shade of a very dense orange tree. Take note here: that's 389 uW/cm^2 for the UVB part of the UV spectrum ONLY, and does not indicate the intensity of UV in general... but since I don't have another $200 to buy a digital UVI meter, I'll have to take a guess here. :) I know my little beardie would bask in these conditions though - I've taken him outside he sits on a rock happily in the sun. Would my water dragon tolerate this if I could handle him? Probably not. I know a couple people who keep aussie water dragons outdoors here and they do seek shade in the middle of the day. It's too intense and hot/dry (and I think they are meanies for raising their AWDs outdoors in the middle of the desert, but I digress).

    I imagine this suffices to demonstrate that the 85 uW/cm^2 I supply my reptile is clearly not harmful - it would be like basking in the morning or evening.

    How can I compare bulbs?
    You absolutely CAN compare setups, bulbs, etc. because what really matters is the intensity of the light the lizard is receiving. Whatever the distance, whatever the screen, whatever the bulb... all that really matters in the end is the UVB radiation hitting your reptile. Honestly you might consider choosing your bulb(s) based on your setup. If your lizard can't get close enough to the bulb, either change that or get a higher intensity bulb (note that this only works up to a certain point, remember how light attenuates!) That is what I've done personally, anyway - I don't have a reflector, so I use 2x 10.0s at 7" from my water dragon. When/if I decide to get a reflector, or whether I just cover the inside of my fixture with aluminum tape, those bulbs may need to change.

    - For diurnal basking reptiles, throw that old notion "5.0=forest, 10.0=desert" right out the window. It's utter nonsense. My writing is not directed at crepuscular/nocturnal/chams as I am not adequately educated about them.
    - Offer your reptile the opportunity to choose the UVB intensity it desires.
    - If you need more light without adding much more UVB just get a ZooMed 2.0 or analogous bulb. This gives the lizard more UVA+"visible light" to use.
  13. SpidaFly

    SpidaFly Elite Member

    Oh by the way - if you want to make a real cheap reflector, line the inside of your plain fixture with an aluminum tape. I used the cheapest on the shelf because it was what I had laying around in the garage at the time - FlexFix by berryplastics. 8" from the unreflected light was in the low to mid 80s uW/cm^2 range. And now 8" from the reflected light is in the 100-115 uW/cm^2 range.

    Is this going to be as effective as Arcadia's parabolic reflector? No, because a parabolic mirror is the mathematically perfect way to get your light reflected where you want. But if you're looking for a quick fix to increase the efficiency of your UV source, it's worth spending 15 minutes on the project. (Heads up: YMMV, if you have a white fixture you might not see as dramatic of results. I used a hardware store T8 fixture, so it was black, hence some pretty dramatic results.)
  14. DwarvenChef

    DwarvenChef Elite Member

    As for the 5.0 issue in my case was from reading others breeding reports stating that their colony did better with the 5.0 bulbs. So I have been basing all my lighting nees on these bulbs. Now I want to know more about their set ups to understande WHY they reccoment the 5.0 for Emerald Swifts. I would expect that other sceloporus would do fine under high intensity, hard skinned Daural basker.

    But what effect does altitude have on UVB/UVA radiation? Emeralds are generally high altitude lizards... wouldn't the UVB/A be more intense at 9k feet?
  15. SpidaFly

    SpidaFly Elite Member

    I'm not personally well educated in exactly what effects weather has on the attenuation of light, beyond the sort of "obvious" thought experiments. What's worth noting however is that the majority of UV blocking is done in the upper atmosphere, not the lower atmosphere. Thus relatively "tiny" elevation changes MAY not be as dramatic as we would initially think, and the majority of reduction of light will come from clouds etc.

    Here's an interesting graph from

    Ah, cool - some data from Honduras and Hawaii, both probably somewhat representative of your Swifts' natural UV-climate!

    I don't know much about Swifts - all I really know is that they're equatorial (see above graph) and diurnal, where the UV is going to be nice and high- so the questions you could consider are: do they are bask heavily in the wild? What times do they typically bask in the wild? Do they burrow during the height of the day (ie. close to no UVB) or just seek the cover of forest? Or do they bask all day (in which case the limit is fairly high).

    As far as the recommendation to go with 5.0's... well, if they are saying the "colony did better", how did they measure and control that? Did they have adjacent colonies with differing levels of UVB? Was this done over the course of years where reproductive health could actually be charted? Were they able to actually measure the UVB, what distances were the reptiles from the source, and did they routinely change their bulbs? Did they control for all other factors such as stress? Unfortunately there's going to be a lot of handwaving... so critical thought (and a chat with a herp vet) is probably your best bet when it comes to these things.
  16. Vers

    Vers Elite Member

    Right, but you also need to factor in UVB intensity drop-off as the bulb ages. From my understanding many standard t8 fluorescent UVB bulbs will put out ~1/2 the UVB intensity at equal distances within a few months time (I can't remember if I read this on UV guide or not--I'll look for the source). By this time you're looking at a working distance of around 4" or so for any effective UVB output at all, which is ridiculously close. At least with higher rated bulbs you can filter or start out at a longer distance and work your way in, either by lowering the bulb or raising the 'basking' surface, as the bulb ages, thus giving the bulb a longer life than that of a lower rated UVB bulb. But unless the keeper has a UV meter he/she will basically be playing the guessing game, hence the reasoning behind automatically changing a UVB bulb every six months or so (the truth is some have been known to go 18mo and over while still retaining respectable UVB output). But yes, I totally agree with your main premise--it depends on the setup.
  17. SpidaFly

    SpidaFly Elite Member

    Well, of course - nothing in my writings indicated otherwise. One of my "conclusions" is that 5.0 bulbs are completely worthless for reptiles that bask heavily. And of course what you said is why it is common knowledge that UV tubes need to be changed every half a year. I don't wait for 6 months to elapse, rather I replace mine when my UVB meter convinces me that the intensities are low (I also stagger replacements so at least one tube is burning more brightly than the other - saves a little money that way). Actually, something kindof cool: ever just LOOK at a brand new UV tube next to one that's just a few months old? The difference can be easily seen with the naked eye.
  18. Vers

    Vers Elite Member

    I didn't mean to insinuate that you thought otherwise, it just wasn't noted so I figured I'd shed light on that detail :)

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