I really like the 405's and have a number of them on our smaller tanks but for the 240 we decided to go with an FX5 along with a pair of modified emporer 400's. One of the features most often overlooked about the newer designed cannister filters like the FX5 is the ability to backflush the mechanical portion of the filter without opening it. This can be used during water changes and greatly decreases the time you spend cleaning out filters.