Personally I think you'd have enough flow w/ the can and the 2 koriala 3's. I'd put the purigen in the can (if you're going to run it constantly) and save the HOB
to slap on the back when I want to add a micro filter to polish the water or run some type of media in a one off fashion. That's what I do for my SW
. For my 30G fresh I just run a 404 and nothing else and a tiny HOB
for a one-off media run.