How about some critter keepers (come with lids) or plastic tubs for the additional tanks?
I have the Marineland Stealth 100W Heater in my 20H... unplug it everytime I do water changes. I'm going to the Marineland website to see if I can get more info on serial numbers effected and such. My heater has worked really well so far and has been right on the money, temperture-wise, so I'm disappointed to hear about this problem.
I checked out the link someone posted on page two (Sorry, like 'Dori' from Finding Nemo, I suffer from short-term memory loss) that went to a forum - and a claim that a 75 gallon tank exploded because of the heater.
Things that make you go "hmmmmm": I did not see any close up pictures of the heater (The first picture showing the damaged tank, the heater is shown in position; doesn't appear to look damaged).
Also, he says the one large fish that was the resident of the tank survived the explosion.
Call me a skeptic, but I'm not convinced the heater did the damage claimed. I'd have to see more evidence... forensics, forensics...