UVB distance for rads

kelogz08

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Hello everyone,

Yet again i have a question regarding how high should the uvb lamp should be from the tortoise shell. I have looked around the forum to find out that some people have their uvb fluorescent bulb 8 inches, some says 10, some says 12 inches, and some says as close to the tort as possible.

I am using a reptisun T8 18inch in one fixture and a exo terra t8 18 inches on another. Both are 10.0. I also use a 25w halogen lamp in a dome that gives around 100 degrees basking spot. All lights are on from 6am to 8pm. I have the tort in a closed chamber using a 75 gallon tank. Humidity runs 60-70% during the day 80% at night. I use a humid hide made from cutout plastic shoe box. Substrate is all cypress mulch

I want to make sure that everything will be optimal for my yearling to have a smooth healthy shell without burning the eyes

What should the distance of the uvb lamp be from my little guy?

ImageUploadedByTortoise Forum1497564695.530600.jpgImageUploadedByTortoise Forum1497564712.251674.jpg
 

Markw84

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I agree with 10 - 18" as recommended for a T8 10.0. However, you state you have two bulbs which is doubling that output. Depending upon how close to each other they are mounted, it can make a big difference. A UV meter is the only way to know for sure. I would not have two 10.0 bulbs mounted next to each other at 12".
 

Tom

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For those types of bulbs I get a very low reading of 1.1 on my Solarmeter 6.5 at a distance of about 10".

I wouldn't get the bulb any farther than that. You might consider a different bulb if it needs to be mounted higher than that. There is also no substitute for putting a meter under your bulbs in your enclosure. That is the only way to do this. Otherwise we are all just guessing.

That water bowl is a flipping/drowning hazard. They are great for lizards and snakes, but unsuitable for tortoises. A terra cotta plant saucer sunk into the substrate will work much better.
 

kelogz08

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ImageUploadedByTortoise Forum1497584877.755049.jpg

This is how close the fixtures are to each other. I would say 4 inches apart.

I am guilty about that ramp bowl. I am currently looking for a clay saucer. I'll be looking at home depot or lowes

Thanks for all your input. I'll bring it down to 10 inches from the substrate
 

Markw84

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They are next to each other lengthwise so there is no doubling effect. As Tom commented I also have found the T8 gives pretty low readings, and the solarmeter an invaluable tool.
 
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deadheadvet

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With the bulbs I am using, The bulbs are set at 18". That being said, I do use a UV meter to get the distance correct.
 

Sterant

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Another solid vote for getting a UV meter - that way theres no guessing - just set the bulb height to the desired reading on the meter. The quality of the reflector you use can literally double the downward intensity of the UV as well, so consider that. I have no problem getting the same reading inside with a 2 HO 10.0 tube fixture as I do outside at noon in the sun.....and my bulbs are 10" to 12" above the substrate.
 

kelogz08

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Thanks guys, amazon sells the solarmeter for $237. Pretty steep
 

Markw84

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Here is another option that is far less expensive. I have had one for a couple years. I don't like it as much as a SolarMeter, but it does the job and is inexpensive. For iPhone and Android.

https://www.amazon.com/dp/B01917YSX2/?tag=exoticpetnetw-20
The problem with UV meters, it they are dependent upon the quality and type of filter used for the sensor gathering the light to give you a reading. The less expensive meters, like this one, is really only going to give you any reasonable reading in sunlight. They are useless and not designed to be used with artificial light coming from fluorescents or MVB, or HID, etc. Some of the better, but less expensive meters also are very limited and are designed so they will read Fluorescent more 'accurately' but not MVB bulbs.
 

Sterant

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I am absolutely a "you get what you pay for" kind of guy, and that holds true here.....its 1/10th the price of a Solarmeter. However, I do get very consistent readings with that iphone meter time after time on the same bulb at the same distance ....at least good enough to watch the degradation of a bulb, or notice a bad one out of the box. But, as I said before, the Solarmeter is better.
 

Cowboy_Ken

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I am guilty about that ramp bowl. I am currently looking for a clay saucer. I'll be looking at home depot or lowes
. You can find those planter bottom pans at most any garden center or nursery, also most hardware stores carry them. Some that I noticed is that you are using a pair of dial gauges for the temps. and humidity ImageUploadedByTortoise Forum1498491355.151398.jpg but as most will tell you the better choice are the digital readers. These typically are more reliable and they are not very expensive at all. What's best is they normally have a wireless remote and a base unit ImageUploadedByTortoise Forum1498491533.448708.jpg allowing you to view your levels while you watch TV in the living-room. Then, if you notice a problem you can deal with it, rather than regularly checking things out. I know you weren't asking about this but I saw it and felt it needed to be addressed.
 

kelogz08

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hi ken, thanks for the input but i have already replaced the analog hygrometer with a probed digital one and also replaced the ramp bowl to a terra cotta saucer
 

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