My next question for you Tom is now that your using strictly infrared heat to heat your tortoise your absence of the rest of the visible spectrum must be substituted.. So what are you substituting for the visible part of the spectrum so your tortoise can 'see'. You can't just use a UV tube because it doesn't have "full spectrum" irradience. So what is being substituted for this 'seeing' light?
I intended to get more into the specifics of this new experiment when I started my other thread, but this is a great discussion and I think talking about it here is warranted.
First I think explaining the "why" will help the "how" to be more understandable. It is my supposition, based on conversations about the wild and captive observations over many years, that newly hatched sulcatas do not bask and don't experience much of a thermal gradient in the niche they occupy. It is my totally unproven, but educated, guess that they dig out of their nests, run for cover under thick brush, and stay there. I can't even begin to guess what the temperature under their bushes is, but because its the rainy season, I know the humidity is very high under there. If ambient temps are 100-110 with the sun beating down on the top of their underbrush, its got to be at least in the 80's under 2 or 3 feet of heavy brush, right? So, I'm guessing on the temperatures, but my intention is to have hot temps during every day, warm temps all night, 80%ish humidity all the time and a 12 hour day/night light cycle.
My closed chamber enclosure is about 22" tall inside and the RHPs are mounted to the ceiling. I doubt the tortoises can perceive any heat from them at ground level. I'm using them to maintain my day and night ambients and they are the sole het sources. Enclosure is about 6 feet long and 3 feet deep.
Now to answer your question and explain the heating and lighting: Its a jumbled mess of confusing wires, timers and thermostats but it makes sense when explained item by item. Well... it makes sense to me...
1. I have two 12x12" 40 watt RHPs on the two ends of the enclosure set on one thermostat to maintain 80ish, day and night.
2. I have a timer set for about 12 hours a day for a 48" 5000K florescent tube. Roughly 7am to 7pm.
3. Set on the above light timer's circuit is another thermostat set to 90 degrees and hooked up to an 80 watt 12x21" RHP mounted over the middle of the enclosure. So for 12 hours a day, the light is on and the enclosure slowly heats to 90ish, as if the sun were beating down on their underbrush and warming it all up. I have a basking rock under this RHP and light, but they don't use it.
4. Finally, I have an Arcadia 12% HO bulb mounted in the middle of the ceiling and it turns on for about 4-5 hours a day, mid day.
So the "sun" comes up around 7am, it gets really bright and warm mid day with higher UV, and then the sun sets and things begin to cool around 7pm. The 6 hatchlings have been in there for over a month and they are growing and thriving so far. No issues of any kind to report, and their carapaces are super smooth. Babies also get soaked daily and taken out to a large tub for some real sunshine for about an hour 3-4 times a week, weather permitting.