Using LEDs

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Re: Using LEDs

Postby RipJohnson » Thu Feb 25, 2016 11:58 am

So I changed where my fixture so that it is directly above the basking spot(Getting a UVB of 110) instead of the front of the tank aiming down and to the back. Now crimson lays directly below the light 2" from it. If you refer to the picture of the enclosure he lays at the top of the log. Do you think i should some how change this? The uvb reading I get is close to 280 in that spot. He is a rescue he has some mbd going on, his jaw is funny. So im not sure if he is doing it because he needs it or because he's a little slow.
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Re: Using LEDs

Postby CooperDragon » Thu Feb 25, 2016 12:13 pm

If that reading is accurate, I'd try to keep him a bit further away. He may like getting the extra UVB but based on what I've read, that intensity can be harmful. The ranges considered to be harmful are UVI 7/8 and above, although limited exposure at these levels may be OK - a lot of this is educated guesswork. That puts the uW/cm2 at around 150+ based on test results on lamps using both the 6.5 and 6.2 side by side. uW/cm2 readings of 280 put UVI in the range of maybe 14-15 or so which is quite high. This is why it's generally recommended that basking spots be placed in an area of 3-5 UVI or so which reflects mid morning and late afternoon levels in their natural habitat. That would be around 60-105 uW/cm2 but that's just a rough guess based on side by side test results I'm reading. The correlation isn't exact.
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Re: Using LEDs

Postby Taterbug » Thu Feb 25, 2016 12:17 pm

RipJohnson wrote:Thank you.
So i read over that uk website way out dated the study was done in 2004to2005 im not sure if t5Ho where even out. Im going to do some experimenting with the 23 watt t5 ballast and the 54 watt T5ho ballastboth with reflectors and w/o and I even bought a mvb to do some testing on. From what i under stand there is a formula to convert uvb to uvi I think. But I think its just a estimate. its UVB/30
no that can very a lot. if its right my uvi is around 3.6. Is your 36 fixture a HO?


The UV Guide is still pretty relevant even if the reports are older. They have a new site (I'd need to find the link) as well as a group on Facebook (reptile lighting) and Fran and some others are pretty active there who can really help with the science of it. They also have test reports for the T5 bulbs and other bulbs with UVI and UVB irradiance readings.

The conversion formula is specific to each bulb. I think I remember seeing a list somewhere but since the spectrum of UV bulbs are all different and different from the sun there is no set formula.

I would not let them that close to a T5 bulb. Coopers estimate is accurate, I can't measure right now but close up my bulb reads a UVI of 13-15, much too high. Dragons can see UVA but not UVB, and again, our lights are not balanced the same as sunlight and have a lower proportion of UVA.
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Re: Using LEDs

Postby RipJohnson » Thu Feb 25, 2016 12:46 pm

The actual basking spot is at a UVB of 110. The spot that he was sitting in it was only his back that was close his head was actually above the reflector. I have to check when i get home this afternoon to see if he went back up there. If he is i guess ill have to take the log out of there.
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