seeing as Australia is a british colony you would probably use the imperial measurement, same as canada. 4.54 litres to a gallon. so your tank is 254 gallons over here in canada. in the states their gallon is smaller, 3.78 litres, so down there its 302 gallons. hey i wonder if its standardised for tanks and everyone uses the same measurement. either way, its still nice. what are the dimensions? 7ft by 2ft by 30in deep? thats how big mine is and it was bought as a 265 gal. its now too small and i want a bigger one