I like that idea. :)
Actually I'm most fond of fluidized beds, and while I haven't worked out
the cost, I suspect it's more economical to have one big one than to have
multiple small ones.
I'm a hobbyist with multiple tanks, and one of my future projects is to
make all of the tanks a recirc system utilizing a fluidized bed. The
maintenance would be greatly simplified, and I think I could built it
inexpensively. The pump to push the water would be the most expensive item,
and that wouldn't be very expensive.
Denise