I haven't used those, but I have seen them in person and used larger ones.
1. That cage should hold a chondro for about a year.
2. I would heat it with a clamp lamp, using a red or dark purple "night" bulb running 24 hours per day. You can't put the clamp lamp directly on them, but you could clamp it to something to where it's shining down onto the cages. Get a temp gun if you want to know if you're getting the temps right. Of course, they may be able to make them for you with a screen hole in the top so that you can put a dome light directly on it.
3. You could use an undertank heater, but it would have to work very well to get the ambient temps high enough at perch level. Of course, if that didn't do it, you could mount the UTH to the back of the cage. Again, the only sure way to know that the temps are correct is with a temp gun. A digital thermometer would work, but they're not nearly as convenient.
4. I would also ask Paul (the owner) and see what he would use to heat those little cages.
>>You have used these 9x9x9 cages for little guys.......wuts the best way to heat them. dont want to cut my 4' heat tape for the little cages.....yet i dont want a bulb to keep me and the snakes up at night. Was wondering if a bottom of the tank heat pad (the kind you stick to the underside of glass tanks) with a peice of melamine separating the small pad and the acrylic would work. Also how long do you think ill be able to keep my Jayapura pair in these cages (if they are indeed a pair...candled) Thanks man i do like those guys am thinking of getting some adult cages made and also going to attempt to make some breeder woma cages out of acrylic for myself in the future lol i should have made these im a fricken carpenter! Oh well Thanks much lookin forward to the cages, know if the would just get here so i can temp them out and get ME SNAKES SHIPPED!!
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Anthony Caponetto
http://reptiles.drivennewmedia.com