if you purchase the 11 inch wide heat tape in 2 foot sections I find that works best for me. I use this on the far side of the cage so it only heats about 1/3 of the cage and then gives the animals plenty of room to self regulate.
If you notice the bottom shelf of this cage we built you can see the heat tape on the left hand side. This gives the cages plenty of heat and it is easily adjustable depending on your thermostat.
The only note I have is if you have a setup like ours, 1 thermostat will not really do what you need. This is because the top and bottom cage stay cooler then the middle cages. I have 1 thermostat controlling the entire setup, but I also had to use Dimmers to keep the middle three cages on about 75% power so the top and bottom can catch up in heat.
Hope this helps.. email if you have any questions.

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Thanks
Shawn Morelan
www.SouthernBoids.com
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