Yes, that is correct. I used an aquarium circulation pump for this (http://fab.cba.mit.edu/classes/863.14/people/matthew_arbesfe...). They go for about 10 bucks on Amazon.

Ah, I skimmed the article but didn't notice that. Thanks for your reply :)

I think you are correct, the commercial models are marketed as circulators so they have both the heating element and a way to move water around to ensure even temperatures throughout the water tub.