looks good! the only suggestion i can think of is switch the baffles around. instead of the first one being a flow over, make it a flow under. bubbles want to go up. so why help them to get past the first baffle.
If you raise the fuge a little higher - more of a gravity feed to the last chamber in the pump intake area of the sump, the water "won't back flow to the fuge. The first "over" divider is higher than the bulkhead and would cause a flood from the fuge.