Need Help with Temps (Using Flexwatt)

I have been using Animal Plastics stackable cages, and I love them. Great humidity and all. Well, they've switched from using heat cable to flexwatt heat tape. Even though I loved my cable, I thought I might try out the flexwatt on this one since I'd never used it before. But now that I have my cage in, I can't get it warm enough. Here's the deal:

Cage is 3' X 2' X1'.
I am using the 11" flexwatt on one side of the cage.
I have the flexwatt on a thermostat, the Zilla temperature controller with probe (pic here: http://www.herpsupplies.com/images/S...Controller.jpg)
Average room temp is around 70, give or take 5 degrees because my house isn't all that well insulated. (Despite this though, my cages with heat cable are just fine, on the same kind of thermostat, and in the same room with the new cage.)
I got the cage set up yesterday afternoon (no snake in it yet--trying to get it up and going at proper temps before I move him), and it has been running since then.
A ball python is going in it, so I am shooting for an ambient temp of 85 and a hot spot of 90, but I can only get the ambient up to 79, and the hot spot is nowhere close. And my thermostat is cranked all the way up.

Any suggestions on what I can do to get my temps up where they should be in a stackable cage?

I thought the 11 inch was the least powerful version of flexwatt. I think you need the 4 inch. Do a search on here, I think I remember someone listing the wattages of each width of flexwatt tape.

Good Luck!
Jim Smith

I think I may have found the problem. I had the cage sitting on a hollow 8" stand, and I think the open area underneath it was causing it to lose heat. I've added some stryofoam to fill most of the void, and have my temps up where they need to be now.

But thanks for the response!

One thing I found out about the flexwatt is that since they weave it over and under every shelf, the closer you get to the end of the flexwatt the cooler the temps get. Because of this my racks are actually cooler at the top shelves than they are at the bottom shelves. I was confused by this at first knowing that heat rises. Are your temps the same in every tub? I believe the longer the length of flexwatt, the more wattage it loses as as you get closer to the end. Must be the same principle as losing wattage if you have a power strip plugged into a power strip etc etc..

I use Helix thermostats and accurite thermometers with a bunch of smaller accurites for every other individual tub. A 6:1 tempgun for measuring accuracy. I still have issues with maintaining temps sometimes. My ambient in the biggest tubs is always about 79 while in the smaller tubs its over 80. I keep the snake room at a constant 80 degrees to help with this. The only way I can think to improve the temp is by starting out with no holes at all punched in the tubs.