Sorry if that was a link to the wrong one, there are a few on the market. I was thinking of something like this-
http://www.gotpetsupplies.com/produc...FREoaQodSYwJZw
As for the wattage of the CHE, having a wattage like 100w isn't necessarily too much, because you will be using the lamp dimmer to modulate down the temps. The reason I say go for the larger heating element is so that you have some room to play with. With a 40w element, it might not get as hot as you need it, while being at a sufficient distance away from the tub to prevent melting. With the 100w you have some room to work with adjusting the temps up or down. You cant make the 40w run any hotter than it can at max setting. The 40w could be plenty, but if you are going to buy something that expensive, you might as well have some room to work with.