Serious dangers of salt water tanks and any tank

[Zoaelite]

Might not be a bad idea with a smaller tank Mike, the only problems I could think of are; The system breaks, you then have to move the tank to repair it OR the heater develops a hot spot, which in turn creates a temperature differential in your glass possibly shattering it.

Having granite tile under the tank would help prevent the second one by heat distribution.

You also then lack the monitoring capacity of a heater, you do get those nasty wires out of your tank though!