Heat Mat Thermostat

I got one of these with some miscellaneous equipment. It has a probe. Can that be stuck in the bottom of a tray in the water or should it be stick in its own rapid rooter?



http://www.gchydro.com/detail.asp?product_id=HYTHRM

i used to just stick it in a pot under my dome,or some people just let it sit on the bottom of the tray,but i like sticking it in a little pot .