Well, I must say: This does work! The only question now is flow. At this point there does not "appear" to be a decrease in flow, but without a flow meter--its hard to say for certain.
Here's some pix--I left them full -size, so You need to click the thumbnails:
First pic is lengthwise through the 36" long tank (40gBr)--doesn't look like there is any water in there
Second pic is front to back with the camera up against the acrylic:
Last pic is back a couple of feet--Please excuse the reflections, etc:
This tank has actually never looked this clean--even after running the vortex itself for 8-12hrs--days at a time. There are only 4 shiners in there now, because the snake has gone into shed and won't be eating until afterwards, but there is up 20+ shiners and 4-5" Comets in there at any given time. As I'm sure You can imagine: Its a particulate heavy tank! Its clear now.
Now I just have to wait and see what the long-term effects are........and how well it works with a heavier fish load, but I think it will work well.
Glad I tried this...............
Side Note: I was wondering about any "Dusting" of the DE on the items in the tank--there isn't any. There was initially, but its all gone now--less than 24hrs later. I don't know how this would go in a plant only tank, but would guess with fish and other moving life--it wouldn't be a problem.
Edit: The above comments about the "Dusting" are not entirely accurate: There is some very slight dusting on a couple of sword plants and the black overflow plumbing--but I had to really look around to find it. I would assume that a Good swoosh around with a hand or something would make it go away easily enough.