Here is how my incubator is setup
The tub with the prob is a dummy tub and only contains the t-stat probe (it is however set like any other tub which mean it contains vermiculite)
Now as far as fan I like small computer AC fans this way I don't worry about the adapter burning out anymore, I use the low speed one for this incubator and it works perfectly.
http://www.coolerguys.com/840556026389.html