In summer here it's hard for me to keep tanks under 28, they will go over 30
if I dont act to control the situation. But the winter I still need them on
the gold coast, They are plugged in for about 3 months a year.
Maybe if you're in Alice, Darwin or Cairns or some place like that you could
get away without one, but you might well need an airconditioner in the
fishes room at those places to keep the tanks cool enough come summer.
Have a look at www.aquariumproducts.com.au they are so cheap there you could
buy one just to experiment, leave it on all winter, if the red light lights
up then you needed it.