UV Readings from Arcadia T5 Slimline Luminaire 39w

[TillyTortoise]

Originally Posted by Alan1

Although they are at the same distance for UVB measurement is it not the case that the tube is set higher than 12" when in actual use meaning a weaker amount of UVB than at 12"? The 100w bulb on the other hand is recommended at 8 inches which would mean it would be a much higher amount of UVB than at 12" albeit over a smaller area

This makes sense, but then it depends what height you need the M.V for the desired 32c basking spot. At 8" I'd get a temperature well over 40c.

[Alan1]

Originally Posted by yuna1971

Well I guess you could hang a heat bulb in the middle of the area...or where the UV is at its most prominent. But again, in effect it would pretty much create the same conditions as what a MV bulb would do, wouldnt it? So isnt it an unnecessary hassle for the same effect? xx

I know what you mean Rach, only the centre of the tube being the max amount of UVB. I was led to believe this bulb was different and the UVB pretty even throughout the length of it but it seems not. The benefit may be more that it's a good bright light

[Alan1]

Originally Posted by TillyTortoise

This makes sense, but then it depends what height you need the M.V for the desired 32c basking spot. At 8" I'd get a temperature well over 40c.

That's true and 8" is the minimum so it could be higher but even dropping or increasing by an inch makes a huge difference to the UVB measurement. Some people have said their 100w has not been hot enough at 8" but of course it depends on the background heat. I have my basking temps at about 36c rather than 32c but they can get much higher in warmer weather but they just don't sit directly under it so long

[yuna1971]

I think primarily tort is going to want heat first and foremost. He gets that range of heat and that range of UV with the MV bulbs.
I just can't see that this strip is going to be any more benefit to the tort if he needs the heat first and foremost. He's not going to sit right by it...and want to remain cool. He'll seek out the heat.
When they bask from what I've seen and read..they move their position all the time. You would have to continuously change the position of the heat bulb to compliment the strips benefit.
I know I'm no authority on all this.. But again from what I've read they don't always want the high dose UV. Would this again support their behaviour of moving around the basking area? I want more heat so I'll sit there...I sense this UV as good so I'll sit here.
I see it as they will dictate themselves where they want to sit in terms of how much heat and how much UV they want. But the bulb gives them the choice, to sit where it's at it's maximum..or just off of it. It's warm too.

Just my opinion..xx

[Ozric Jonathan]

The variation of uvb along the length of the T5 only happens with the luminaire. The luminaire is an elegant all-in-one gadget and I haven't tried it. But in my set-up with standard T5 tubes and reflectors there is no significant variation along the tube in the uvb output.

At a height of something like 12" the uvb level is up to 130uw/cm2 which is really quite a lot of uvb. I don't think there is any reason why it couldn't be hung lower or higher if the keeper has particular beliefs about the amount of uvb that they think their tortoise needs. The 12" was a suggestion. My view is don't hang it lower than that unless you have a uvb meter and are confident about what you are doing.

The area of substrate which is receiving uvb from the T5 is HUGE compared to what you get with a combined lamp. Absolutely massive. And with a combined lamp the tortoise only has the possibility of accessing higher levels of uvb when it is getting a lot of heat at the same time. Once the tortoise has warmed to its desired temperature it will move away from a combined lamp to the edge of the range of uvb output. Unless of course the lamp is too high up in which case the tortoise will sit there all day attempting to reach an adequate temperature.

One of limitations of the combined lamps is the inescapable connection between heat and uvb and the major role that the background temperature plays in where you end up hanging your lamp. The T5 can be placed where the keeper thinks it should be for uvb purposes which allows for better control over both uv and temperature levels.

At the risk of boring the socks off you all, with a T5 tube you can do whatever you like for heat. You could just use ceramic heaters, have some halogen lighting or use plain old light bulb for heat method. You can have it as hot as you think it should be and whatever adjustments you make to your heating it will have no effect on the amount of uvb.

T5 tubes give the keeper a lot more options but yes it is another gadget with cables etc and for keepers who want the minimum of all that then they will be better off with a combined lamp if they are happy with the uv, light and heat conditions they are getting with it.

I'm not trying to convince anyone to try these tubes but I think some of the objections to them just don't stack up. What I've found is that it's very difficult to get the heat, light and uv conditions that I want to provide by using only combined lamps.

Anyone using a 100 watt combined lamp and nothing else needs to understand that the physical area which they are making suitable for a mediterranean tortoise is very very small.

[TillyTortoise]

A very good explanation Jon I was for the most part happy with the combined lamps, although a change in setup didn't allow me to use them any longer. I will take some more readings from the lamps on the weekend and see if there is an actual variation in output along the length of the lamps. The 100 hour burn in time will be done so output should be stable. If the UV output is the same along the length then IMO, they are far superior than the M.V's.
I have all my heat sources on thermostats now and I find it much easier than when I was using the M.V lamps.

[TillyTortoise]

Readings from December 19th

Lamp 1 - 110 uW/cm² at 12 inches.

Lamp 2 - 132 uW/cm² at 12 inches.

Lamp 3 - 131 uW/cm² at 12 inches.

Surprised with reading of lamp 1, I took each reading several times to make sure they were correct.

[egyptiandan64]

That is a decent drop in only a months time with lamp 1. Hopefully it doesn't keep dropping like that and just evens out. Only lamp 2 seems to be holding it's own and not dropping very much, though lamp 3 is only a bit behind.

Danny