I saw this topic header and my curiousity got the best of me. After reading the previous posts, I did a search and found the article espousing this idea of a "uniflow tank".
Sorry guys. This is another example of the plethora of bad information being spread around by misinformed "experts" who badly need to retake their high school physics.
On the otherhand, there are some actual problems with this design due to the backflow problem mentioned and especially the likelyhood of the clunks getting tangled up.
The answer is to hook up your tank like the manufacturers tell you to.
Allan Flowers