How much UV is enough?

[haydog_99]

I’ve read in these forums a few times that if a tortoise gets outside enough a UV light in the enclosure isn’t necessary. My UV light needs to be replaced and I’d rather wait until the temps cool. I take my yearling Leopard outside for about 30 minutes a day, is that enough UV exposure for growth and vitamin D production?

 

[MichaelL]

I'm pretty sure that is enough.

 

[Tom]

I answered another question like this earlier today:

This is a very complex subject with many variables, but the solution is as simple as the problem is complex. No one knows exactly how much UV is needed, or what levels, or what duration, at what temperatures. What about dappled shade? How much UV is lost through a screen or protective wire top? What if the tortoise spends most of its time in the shade?

I encourage everyone to read and learn about UV and tortoises as much as possible, but when you are done, you will realize, like I have, that there are far more questions than answers. Search for any work done by Frances Baines. I consider her the world authority on lighting and UV for reptiles, although recently, I'm starting to think our own @Markw84 may have surpassed even her level of knowledge and study.

As discouraging and hopeless as all these questions sound, its not a problem in any way. There are many many theories, strategies, and recommendations for UV. The only method I've seen that doesn't work well is keeping a tortoise exclusively in a small glass tank with no heat, light, UV, and a diet of mostly lettuce. If you want to see MBD in person do those things, but it will take many months to see damage. From what I've seen ALL of the things we normally do will all contribute to preventing MBD. Supplementation, sunning, indoor UV... All of these help prevent MBD.

I use the "one hour of outside time per inch of tortoise" and my "a couple hours of sun per week" as general easy guidelines for people to follow. There is no specific scientific study to back up those numbers. Only a lifetime of observing hundreds of my own reptiles of many types and species, and also observing other people's reptiles and UV regimes both in person, here on the forum, and also consulting with the many reptile vets I know and work with. I know for a fact that those strategies will work and will keep a tortoise healthy and free of MBD, because I've raided hundred of babies of multiple species following those two guidelines. More than this is fine, and I'll bet a lot less than this would still work.

@haydog_99
If you didn't take your tortoise outside or replace your bulb for the next three months, it would be fine. They store D3 and use it up as needed.

30 minutes a day is plenty of time to meet your tortoise's UV needs and prevent MBD.

 

[haydog_99]

I answered another question like this earlier today:

This is a very complex subject with many variables, but the solution is as simple as the problem is complex. No one knows exactly how much UV is needed, or what levels, or what duration, at what temperatures. What about dappled shade? How much UV is lost through a screen or protective wire top? What if the tortoise spends most of its time in the shade?

I encourage everyone to read and learn about UV and tortoises as much as possible, but when you are done, you will realize, like I have, that there are far more questions than answers. Search for any work done by Frances Baines. I consider her the world authority on lighting and UV for reptiles, although recently, I'm starting to think our own @Markw84 may have surpassed even her level of knowledge and study.

As discouraging and hopeless as all these questions sound, its not a problem in any way. There are many many theories, strategies, and recommendations for UV. The only method I've seen that doesn't work well is keeping a tortoise exclusively in a small glass tank with no heat, light, UV, and a diet of mostly lettuce. If you want to see MBD in person do those things, but it will take many months to see damage. From what I've seen ALL of the things we normally do will all contribute to preventing MBD. Supplementation, sunning, indoor UV... All of these help prevent MBD.

I use the "one hour of outside time per inch of tortoise" and my "a couple hours of sun per week" as general easy guidelines for people to follow. There is no specific scientific study to back up those numbers. Only a lifetime of observing hundreds of my own reptiles of many types and species, and also observing other people's reptiles and UV regimes both in person, here on the forum, and also consulting with the many reptile vets I know and work with. I know for a fact that those strategies will work and will keep a tortoise healthy and free of MBD, because I've raided hundred of babies of multiple species following those two guidelines. More than this is fine, and I'll bet a lot less than this would still work.

@haydog_99
If you didn't take your tortoise outside or replace your bulb for the next three months, it would be fine. They store D3 and use it up as needed.

30 minutes a day is plenty of time to meet your tortoise's UV needs and prevent MBD.

Thanks for the response my tortoise is about 3.5 inches and gets around 6 hours of sun a week so I’m going to hold off on a new UV light until fall.