good idea
i guess as its a more powerfull heater it wouldnt need to be on all night, though could be if it had a thermostat
my only thought is the cost of running the thing, as the people opposite me have a pool and allways moan at the heating costs
the Aquarium heaters cost very little to run
ref the moving of the water , i think if you had 1 heater either end of the tank, that would be enough