Wow ... closed loop recirculation. A revelation when you find out something new that just makes sense. Another newbie discovery! Hmmnnn. Anyone have any opinions on a couple of Reeflo Snapper's for a 200 gallon 45"x30"x36" tank ... one for circulation (closed loop) and the other for the filter/sump circuit? That way, I could bridge the two circuits with a ball union that is normally closed and if one pump dies, I can just use the other to drive both circuits until a replacement arrives. I like the redundancy idea.