Measuring temperature (I am seeing this done wrong 99% of the time!)

turtlesteve

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Sep 23, 2012
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When measuring temperature in a tortoise enclosure, there are two temperatures that you can measure:

- The AIR temperature in the enclosure
- The SURFACE temperature in the enclosure

Both of these are important.

In an enclosed place without light, such as inside a hide box, these temperatures will be almost the same. Everywhere else they will be quite different.
So first of all, why do they both matter and what should they be? We want to make sure the tortoises are not overheated or chilled, especially for hatchlings. So when the tortoise is hiding in a hide box, or somewhere in a dark corner of the enclosure, the body temperature of the tortoise will gradually reach the air temperature. But when the tortoise is out and basking, they will rapidly heat up, by absorbing radiation. This is where the surface temperature matters. So, the minimum air temperature should be kept high enough to prevent the tortoise being chilled, and the maximum surface temperature should be some reasonable value to avoid overheating. I prefer much lower temperature gradients than are often recommended. For tropical tortoises I tend to aim for 80-85F air temperature and 95F surface temperature in the basking area. For hatchlings I will narrow the range even more. Nighttime air temps can drop (and I think this is beneficial). I like 75-80 for tropical species and 70-75 for temperate species. I feel like most of the time, tortoises are being kept under EXTREME temperature gradients that are not beneficial. Part of the problem is that temperatures are not being measured right. The rest comes from people (in the past) pushing extremely powerful basking bulbs and open/ventilated enclosures...

So now with regards to how this is measured:

AIR TEMPERATURE: Should be measured with a probe thermometer in a shaded area (indirect light only). It is not possible to measure air temperature with an IR thermometer but you can estimate it as noted below. Other thermometer types are acceptable (liquid thermometers etc.). If the thermometer is directly exposed to the basking light it will read wrong.

SURFACE TEMPERATURE: Should only be measured with an IR thermometer. However, you will often NOT get a useful reading by pointing the thermometer at some random surface. The surface temperature depends on the surface! IR thermometers will generally give bad readings on white or highly reflective surfaces. The proper way to make this measurement is:

- Find a "standard" surface. Generally you want to make sample coupons that are matte black in color and 2-3" in size. I use cardboard packaging inserts (that were dyed black) and cut them into squares.
- Any time you want to measure IR temperatures, put these sample coupons in the enclosure where you want to measure temperatures. In this case you want the coupon to be exposed to the basking light as the tortoise would be. Let them reach equilibrium.
- Use the IR gun to measure each surface sample and use this as your surface temperature measurement.
- Tortoise shells are very good at absorbing IR and will heat up much more than the surrounding substrate. This method is a better estimate of how hot a tortoise will get than pointing the IR gun at the substrate.

If you only have one thermometer, it should be an IR type. But it is very helpful to have a non-IR thermometer for measuring air temperature. You can estimate the air temperature by hanging a sample coupon in the air, in a shaded area, and measuring it with the IR thermometer.

Steve
 

LaLaP

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When measuring temperature in a tortoise enclosure, there are two temperatures that you can measure:

- The AIR temperature in the enclosure
- The SURFACE temperature in the enclosure

Both of these are important.

In an enclosed place without light, such as inside a hide box, these temperatures will be almost the same. Everywhere else they will be quite different.
So first of all, why do they both matter and what should they be? We want to make sure the tortoises are not overheated or chilled, especially for hatchlings. So when the tortoise is hiding in a hide box, or somewhere in a dark corner of the enclosure, the body temperature of the tortoise will gradually reach the air temperature. But when the tortoise is out and basking, they will rapidly heat up, by absorbing radiation. This is where the surface temperature matters. So, the minimum air temperature should be kept high enough to prevent the tortoise being chilled, and the maximum surface temperature should be some reasonable value to avoid overheating. I prefer much lower temperature gradients than are often recommended. For tropical tortoises I tend to aim for 80-85F air temperature and 95F surface temperature in the basking area. For hatchlings I will narrow the range even more. Nighttime air temps can drop (and I think this is beneficial). I like 75-80 for tropical species and 70-75 for temperate species. I feel like most of the time, tortoises are being kept under EXTREME temperature gradients that are not beneficial. Part of the problem is that temperatures are not being measured right. The rest comes from people (in the past) pushing extremely powerful basking bulbs and open/ventilated enclosures...

So now with regards to how this is measured:

AIR TEMPERATURE: Should be measured with a probe thermometer in a shaded area (indirect light only). It is not possible to measure air temperature with an IR thermometer but you can estimate it as noted below. Other thermometer types are acceptable (liquid thermometers etc.). If the thermometer is directly exposed to the basking light it will read wrong.

SURFACE TEMPERATURE: Should only be measured with an IR thermometer. However, you will often NOT get a useful reading by pointing the thermometer at some random surface. The surface temperature depends on the surface! IR thermometers will generally give bad readings on white or highly reflective surfaces. The proper way to make this measurement is:

- Find a "standard" surface. Generally you want to make sample coupons that are matte black in color and 2-3" in size. I use cardboard packaging inserts (that were dyed black) and cut them into squares.
- Any time you want to measure IR temperatures, put these sample coupons in the enclosure where you want to measure temperatures. In this case you want the coupon to be exposed to the basking light as the tortoise would be. Let them reach equilibrium.
- Use the IR gun to measure each surface sample and use this as your surface temperature measurement.
- Tortoise shells are very good at absorbing IR and will heat up much more than the surrounding substrate. This method is a better estimate of how hot a tortoise will get than pointing the IR gun at the substrate.

If you only have one thermometer, it should be an IR type. But it is very helpful to have a non-IR thermometer for measuring air temperature. You can estimate the air temperature by hanging a sample coupon in the air, in a shaded area, and measuring it with the IR thermometer.

Steve
This is something I really needed to read a couple years ago when I got my first tortoise. I finally figured it out but it would have been nice to read this back then. This is definitely not obvious to everyone.
 
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