new uv, permeable plastic

[Ozric Jonathan]

Thanks John it is good to have that input from you.

My readings through my plexiglass coldframe have shown a slight reduction in uvb transmission in the last two years. Of course, my garden isn't a controlled lab!

In my case, I want the tortoises 'outside' as much as possible in suitable months of the year. With free access into and out of the coldframe during the day, their exposure to uv from the sun is maximised.

For me, the alternative to a plexiglass coldframe would be something similar made out of a material that doesn't allow any uv transmission at all.

I personally don't want to keep animals that never see the light of day.

[Arcadiajohn]

Yes I agree, some is much better than none! If you are pre-informed of limitations.

Let's hope sometime comes along soon, after all the sun is the only perfect light source!!!we can NEVER match it no matter what anybody says.

John

Originally Posted by Ozric Jonathan

Thanks John it is good to have that input from you.

My readings through my plexiglass coldframe have shown a slight reduction in uvb transmission in the last two years. Of course, my garden isn't a controlled lab!

In my case, I want the tortoises 'outside' as much as possible in suitable months of the year. With free access into and out of the coldframe during the day, their exposure to uv from the sun is maximised.

For me, the alternative to a plexiglass coldframe would be something similar made out of a material that doesn't allow any uv transmission at all.

I personally don't want to keep animals that never see the light of day.

[patterkillar]

found link for uvb polytunnel plastic

http://www.lbsgardenwarehouse.co.uk/...sfile=1&jump=8

[Ozric Jonathan]

Looks interesting. I wonder how much uvb goes through it and what the rate of decay is.

Could be a useful material. If anyone tries it please let us know.

[Alan1]

I thought it was going to be the size of those professional tomato grower ones

[romski]

I'm in prison in some mediterranean island and am having to suffer sunshine, bad wi-fi and great cheap wine. The last two being incompatible and are making things worse. I would like to respond about the comment on low iron glass when I get back as I don't have data with me.

In the meantime I would ask a question.
For a temperate climate animal that undertakes basking, lets say a med tort and/or a painted turtle. What are the minimal physiological retirements for uvb index exposure at D3 wavelengths required to sustain a thriving healthy animal?

This is not asking how much sunbathing they do, but asking how much uvb they clinically need. Im separating sunbathing for thermoregulation from sunbathing for uvb utility.

I would use a 6.5 meter as a reference instrument or a 6.2 factored by 0.05 to give a rough uvi D3 value estimate. I am aware that those two instruments measure differing and overlapping wavelengths.

How many uvi index minutes/hours at what level?

Until that question has an answer any discussion on Uvb exposure no matter what the source - is academic.

You first ask what is needed, then you decide how to administer it.

Please take this post as a constructive extension on an interesting debate.

Rom

[Alan1]

Originally Posted by romski

This is not asking how much sunbathing they do, but asking how much uvb they clinically need

I'm only guessing but having seen lots of tortoises that have been denied any UVB at all, my guess is that it's not a huge amount

[Ozric Jonathan]

Andy Highfield madfe a suggestion that a mediterranean tortoise needs to bask for 45 minutes per day. This was based on a number of things including field observations. We know that mediterranean species don't bask under conditions of very high uvb as it is far too hot for them to be out around midday in the summer months.

As I underdstand it, they need to be getting heat at the right level whilst being exposed to the uvb so the calculation maybe has to involve heat as well.

I don't know if anyone has made a measurement of the amount of uvb that is needed in the sense of intensity x minutes.

Mediterranean species are often described as having high needs for uvb but 'high' is fairly meaningless.

Tortoises denied uvb will not grow properly unless they have Vit D supplementation.

[Alan1]

Originally Posted by Ozric Jonathan

Tortoises denied uvb will not grow properly unless they have Vit D supplementation.

That's what I was meaning, there are people who give Nutrobal but don't use UV bulbs so I'm guessing that because the D3 in powder form appears to be enough, they may not really need high amounts of UVB but how would anyone know, there is simply no way of knowing or calculating it. Different torts will probably need different amounts at different ages or sizes and at different locations in the world.

One thing I do believe is that they can have too much, Dazza proved that with his iguana and I've no reason to think torts will be different. My torts behave in a similar manner to that iguana in that they hide from the UVB for weeks at a time and for that reason I'd be a bit concerned about using one of the T5 bulbs along with a 160w UVB combi bulb

[Ozric Jonathan]

Originally Posted by caledonia

for that reason I'd be a bit concerned about using one of the T5 bulbs along with a 160w UVB combi bulb

I think it depends partly on the extent to which the uvb from the different sources overlaps and how high the different sources are above the substrate.