Runaway Heater

[ricosuave]

I've got kind of a stupid question...I use two 44 gallon Brute trash cans for RO and mixing for my 75.(eventually I will have different setup downstairs for the 240) My question is: what is a good way to attach a heater(cheapo heater from Wally World) to the inside of the container(the Brute) so that it wont float up to the top or end up tangled in cords/pumps? I tried the cheapo suction cups that came with it, but they dont hold for long on a round surface.
What do you guys use/do for this?

[olsaltybastard]

I do not preheat the water that I use for water changes. I make the water up a few days in advance, so the water gets to ambient air temperature which is never far off from the temp of the display tank. I have yet to notice so much as a one degree temp change doing this, though it certainly may seem a bit lax.

[CheyDogFlies]

Can you tie a heavy-enough piece of live rock you can live without to it? Perhaps use a large plastic zip tie.