Yes Tony, you can nix the cannister.
It won't do anything more than the sump will do (straining - mechanical filtration and hosting biomedia). You could use bioballs but for a small sump you would get more bang out of ceramic rings or rena chemstars. I've also used plastic pot scrubbers, sponges and pond filter matting - anything that provides surface area. You can also try your hand at creating a F.W. refugium.
I have also lost my mind it seems as I have a 140G. F.W. and only a 75G. S.W.
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RV90