You are correct Dallas - Rod - I think that Riaan is referring to the suggested way of having a sump with only 3 partitions, where one partition is for the skimmer, the second for the DSB and the 3rd partition for the return pump....
Riaan - these sumps' design is not specifically incorrect - it is just the bio-balls and ceramic noodles that come from the fresh water mind-set. This used to be OK with FISH ONLY systems of the past - but in the era where keeping corals is MUCH more of a norm, high nutrient levels is not acceptable anymore.
With the sump designs as you have pictured, there ware always issues with nitrates and phosphates being high - and as I said - with FISH ONLY, this is not a problem.....