You only need to put those dividers (baffles) in the sump if you want to keep the sections separate -- like if you want a refugium in your sump. With mine, I have the refugium in a separate container (the round one), so I don't need any baffles. So I just put all the equipment in the tub and it works great.
I'm so much happier with this setup than I was with the last one -- which was a 55 gallon sump made out of an old tank with baffles.