>>Well, here is what I was thinking - On one side of the reptarium, I would have the usual 100 watt basking bulb with a basking platform beneath. As I substrate I would like to use playsand, which holds and re-releases heat relatively well. Then on the "cool" side of the enclosure I can place a human heating pad, which on a high setting can heat 2-3 inches of sand to 90-95 degrees. I also keep a 60 watt general reptile bulb on the "cool" side just to help ambient temps. To me, this setup would seem sufficient, but I may not be thinking of something...
You can sure try that, but I think unless the ambient temperature in the room is fairly high you will have a hard time maintaining a decent gradient.
You talk about a heating pad raising the sand temp to 90-95 but that is a "basking" or surface temp not an ambient temp.
Quick rundown on basking vs ambient and how I measure them.
I measure basking temps with a non-contact infrared thermometer (temp-gun) which is the only reliable way of doing it. This measures the temperature of objects in the enclosure (rocks, substrate, basking platforms) and tells you what sort of temperature will be conducted to your reptile by direct contact with the object and give you some idea how much heat your reptile will absorb by direct radiation in that same location. This is important because it lets you know how much belly heat the reptile will get when in contact with that object and how quickly the radiated heat will warm up your reptile. For Uros I like to have several different areas of basking temps that run from 100-140 (for adults and older juvies, and a max of 120-130 for babes)
Ambient temps I measure with digital probe thermometers but can be measured with accurate dial thermometers. The important thing to remember when measuring ambient is to not let the thermometer come in contact with any surface or substrate and preferably be in the shade, especially with dial thermometers as the clear glass will capture the radiated heat turning the inside of the thermometer into a mini sauna giving you a false reading. The thing for your reptile with ambient temps is that they can never be cooler than the ambient temp (since they don't have any significant way to cool themselves) and will be no warmer than ambient unless they are getting additional heat from conduction or radiation (which is your basking temp). For Uros I like an ambient gradient that runs from 80-85 on the cool side to 95-100 or a touch more in some very small controlled spots on the warm side.
As you can see with an open air enclosure all of the ambient temps are likely to be the same as the ambient room temperature. Even if you were to have some nice warm rocks at 100 degrees radiating that heat and heating the air, that air will rise through convection bringing in more room temperature air.
So while an open air enclosure may be possible in very warm climates with no air conditioning (as someone posted previously) unless you are willing to heat an entire room you will be fighting an uphill battle to maintain a proper temperature gradient. Even in a warm climate you will probably have problems keeping the ambient temps on the cool side cool enough.
Sorry about the dissertation but I have seen a lot of confusion about basking vs ambient in other discussions and wanted to try and help clear it up.
Of course this is all my personal experience and opinion and should be taken as such. There is more than one way to do things so you should try things out for yourself (without an animal hopefully) and see how they work.
Just keep measuring those temps all the time and in multiple places.
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Mike Wilson
mwilson@fuu.net
