Hey snakeskinner =), I do keep my waterline up, but with this filter and the 20 gallon long, it's to the point where i'm adding water to fill it up to the maximum every night before i go to bed, and even filled to the maximum, the sound is still annoying. It's not annoying to the point where i'll go insane, but it does take me longer to go to bed, because of the noise. And i completely agree with you about the design of the tank!!! It does the exact same thing, going across the top of the water, off the glass and into the substrate!!! There is a long horizontal stripe at the very front of my tank about 10 to 12 inches where the sand is pushed away and the glass shows. I had the same thought about dropping down to a lower filter, i wanted to avoid spending more money, but it's really not that much money, a penguin mini should be less than $20.
In the tank, i have 4 panda corys, 2 clown loaches and one tropheus maswa. The tropheus, i'm trying to find a good home for, as I read that he is happiest w/ a big group of his/her own kind. I have a 20 gallon long, w/ black sand for the substrate, thinly spread, maybe 1/2 to 1/4 inch thick, in the tank is one piece of driftwood and 3 small pot/caves. I was happy w/ the 200b penguin filter because the powerfull flow managed to pick up alot of the dirt, while leaving the sand alone (except for that stripe at the front), but I think i will buy a smaller filter and see how that works. Thanks alot!