# UV light and glass top question



## hobbyuniverse (Jun 22, 2008)

I have an Exo Terra terrarium that will be home to a couple leucs in about a week. It has a screen top but I just had some glass cut that I will lay on the top to cover the screens. My question is how much uv light does my viv need (frogs and plants) and how much will be blocked by the glass? I want to raise my light fixture with some feet to better regulate the temps inside, especially once the glass is in place. My light fixture is also by Exo Terra and uses two 26w Reptiglo 5.0 UVB bulbs.

Does it evcen matter that I will be laying the glass under the light?
Thanks


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## nish07 (Mar 16, 2008)

Half your UV will be cut out by the screen. Even if the screen weren't there all of your UV is cut out by the glass. The best thing to do is to get some Solacryl and put it on the top (I'm trying to figure out the best way to do this myself) and remove the screen altogether. The Solacryl will block something like only 30% or less UV at 3/16" thickness.

-Nish


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## nish07 (Mar 16, 2008)

BTW, your leucs probably don't need UV.


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## hobbyuniverse (Jun 22, 2008)

Ok, so my leucs dont need uv? Do plants?


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## nish07 (Mar 16, 2008)

Nope. Your plants will get by fine without UV bulbs. You could probably do best with T5 6000-67000K bulbs or power compacts in the same color temperature range. T5HO seems to be the light of choice these days but it's hard to find something decently priced.

BTW, I don't know how the hood of your Exo Terra is constructed, but if you plan to put glass over the top (and remove the screen which you should do), you don't wanna get those PC bulbs too close to it or the glass will crack. You might need to raise them and probably should to keep the temps reasonable in the tank. You'll have the temp problem because the glass will seal the tank so you get the greenhouse effect. A small screened section would be ok (like a strip of it) to allow some ventilation, but you definitely want a lot of glass covering it so you don't lose all your humidity (which should stay at least around 80 percent).

-Nish


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## hobbyuniverse (Jun 22, 2008)

Thanks for the response. When I had the glass cut, I had it cut in 3 sections so I could remove/add panels to adjust heat. The glass panels are actually cut to lay on top of the screens so for now I cant remove it. The bulbs I bought dont have a color rating that I can find. The ones I have are these:

http://www.exo-terra.com/en/products/compact_fluorescent_bulbs.php

They are second down in the green boxes. So far my plants love them. 

I have a hygrometer on order that should be here this week so I can monitor humidity. It stays pretty humid in there as I mist a couple times a day. I am treating my terrarium like the frogs are already in it so that when I do add them the plants will be used to it and I wont get any surprises. Fruit fly and spring tail cultures are going storng. Now I just need my leucs!

Im already eyeing larger tanks to build a much bigger setup, but I will wait a year or so that Im very familiar with everything before taking on a larger project. 
The 175 gallon at the local pet store is calling to me.... :shock:


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## nish07 (Mar 16, 2008)

How big is your tank and how many watts is your hood/fixture rated at? The color temperature bulbs for growing can be pretty cheap (5-10 bucks a piece). I just did a quick search and found a couple right away. There might be some more suited to growing plants for people more serious about getting the most out of their lights but the cheaper ones would work, especially if your tank isn't that large.

-Nish


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## hobbyuniverse (Jun 22, 2008)

The hood I have is rated at 26w max and holds two bulbs. My tank is the 18x18x24h version. Im not too concerened with the cost of bulbs, within reason. I have been throwing money at this for the past few weeks and havent gone broke yet! My main concern is having this setup right before the frogs arrive. I dont want to come across as paranoid but I really want to avoid any mistakes. 

With that being said, this forum is an EXCELLENT tool for someone like me that likes to research stuff to death. For me, its part of the fun! (sick, I know...)


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## nish07 (Mar 16, 2008)

Light is more for the plants. However, the Leucs will like heavily planted tanks with plenty of places to hide. Don't use a bulb with more wattage than the hood. Find a cheap power compact in the 6000-6700K color temperature range. Raise it off the top of the glass by about 1-2 inches depending on how much heat is generated inside the tank. The leucs will like it around 76-78 degrees.

-Nish


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## zeus_rous (May 9, 2008)

I dont believe that regular glass blocks the uv. On my saltwater tank I have a double ended metal halide light that requires tempered glass to block the uv rays.


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## sports_doc (Nov 15, 2004)

Does anyone have data on the UV penetration of standard glass. 1/4 inch, 3/16inch, 3/8 inch ect.

??

S


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## kristy55303 (Apr 27, 2008)

my first viv was an 18x18x18 exo and the hoods made for the exos are lifted up with the bulbs inside with reflectors. my plants flourished with glass. no problems. kristy


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## Corpus Callosum (Apr 7, 2007)

sports_doc said:


> Does anyone have data on the UV penetration


parts-construction/topic39026.html


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## dwdragon (Aug 14, 2008)

I am currently using the 2.0 bulb instead of the 5.0 bulb. From my understanding in reading on the website and asking questions the 2.0 is more suited for plant growth where as the 5.0 is for tropical reptile calcium absorbtion and the 10.0 is for desert reptile calcium absorbtion.

The 5.0 bulb has added uvb rays which are going to be blocked by your glass anyways where as the 2.0 bulb has mostly uva rays and is a full spectrum bulb in the color range suggested for tropical plants.

I have a 3 light hood I might play with it and try mixing in 1 x 5.0 and 2 x 2.0 to see what that does to plant growth versus just the 2 x 2.0 I have in there right now. The only thing I will say that is a con of using these exoterra bulbs is that the highest wattage is 26w. I have a 56 gallon column tank and I'm a bit worried about the light reaching all the way to the bottom. I'm not sure how it works if you have 3 x 26 watt bulbs. I don't think it extends the light range tho I'm not sure. I believe I read somewhere that a comparable bulb would reach an effective depth of 12 - 18". I'm considering changing the hood and getting a higher wattage standard flourecent bulb to reach farther down in my tank as I will be redesigning it to utilize more height.

Just thought you might want some of the tidbits of information that I've picked up from the research I've been doing.

Another determining factor for light is the type of plants you have. I have some that prefer some sort of filtered sun or partial shade and will burn in bright lights. This is something to keep in mind when looking at plant placement and bulb wattage. I do like the exoterra hoods for that reason because the one I have allows up to 3 light bulbs I can plant the lower light plants on one side and only put in a 13 watt there and plant the higher light plants on the other side with a 26 and 13 or put all 26's which is what I'm going to try due to the effective penetration range for the light.


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## nish07 (Mar 16, 2008)

I happen to be trying Solacryl acrylic. Though it may warp, I'm framing it in aluminum to try and keep that to a minimum (at least the edges should stay flat). Solacryl up to 3/16 (I believe) only loses about 30% UVB transmission. I'd imagine, since I'm using thinner, I'd get better results. A screen top will reduce UVB from a standard bulb by approximately 50%. Regular glass doesn't transmit UVB at all which is what is (arguably) beneficial for frogs (especially pumilio) to synthesize D3.

-Nish


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## Virulent (Sep 9, 2008)

nish07 said:


> Regular glass doesn't transmit UVB at all...
> 
> -Nish


Sorry, but this is incorrect. Standard glass does indeed allow a small amount of UVB to pass through. Such glass is nearly transparent to UVA but is partially opaque to shorter wavelengths, such as UVB. UVA has a wavelength range of approximately 400nm - 315nm while UVB is rated from 315nm to 280nm. Tests conducted on standard glass have shown that glass passes roughly 90% of the light above 350nm, but blocks around 90% of the light below 300nm. It's safe to say that up to 15% - 20% of the UVB hitting the glass is actually getting through.


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## nish07 (Mar 16, 2008)

Check out www.uvguide.co.uk for more info. They've done quite a bit of testing.

From this particular page www.uvguide.co.uk/uvinnature.htm

*Glass and Acrylic Sheeting
We tested the transparency of various substances to ultraviolet light. 

"Crown glass" - window glass and aquarium/ vivarium glass - Fig. 11. No UVB reaches these bearded dragons through the window almost completely blocks UVB. A meter aimed directly at the sun through one double-glazed glass window recorded 2uW/cm² when the unobstructed reading was 147uW/cm² - over 98.5% was blocked. Through other windows and several glass vivarium panels, a 100% block was seen. Reptiles living indoors behind glass are unlikely, therefore, to benefit from natural UVB from the sun.


One of the authors was fortunate enough to visit a large private collection of European and Eurasian lizards housed in Sussex, in outdoor enclosures and converted glasshouses. Fine quality horticultural glass used in one greenhouse proved little better than ordinary glass: 97- 98% of the sun's UVB was lost.*

-Nish


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## Virulent (Sep 9, 2008)

Very interesting! I guess in general that's just a problem you run into. Different studies can get different results and then you just don't know who's more correct. These guys seem like they did a solid job. Thanks for the link.


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## stemcellular (Jun 26, 2008)

Having used both Exo Terra 2.0 and 5.0 compacts I'd say dump one of the 5.0 and replace it with a 2.0. Once I did this with my 18" cube the plants really began to flourish.


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## Enlightenment (Mar 26, 2009)

nish07 - perfect link and info. Had no idea that fine quality horticultural glass used in one greenhouse proved little better than ordinary glass: 97- 98% of the sun's UVB was lost. KISS or keep it simple applies in the case of the glass you use too I guess.


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## Corpus Callosum (Apr 7, 2007)

Old link isn't working anymore so reposting..

http://www.dendroboard.com/forum/parts-construction/28379-starphire-grades-uv-transparency.html


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