Well, usually, if you about 1 to 1.5lbs of live rock per gallon, you do not need the cannister filter as the live rock and sand bed provide all the filtration that is needed..I have a cannister filter on my current setup, as advised when i first started out, but, after seeing the nitrate levels higher than i wanted them, i took more advise from the people on here and i removed all the guts out of the filter and just use it now for extra circulation..If i had known this form the start, i would not of brought it to be honest..But, that is what its all about, learning, and rectifying the mistakes and passing on the advice to others..
Niko