Very interesting thread. I might just come to you for a bit of advice. I am also setting up an Amazon tank soon. Mine is a little over 300 gallons (sorry, don't work in litres) anyway, dimensions 8' x 2.5' x 2.5'. I'll be using a 66 gallon sump filter as well.
. Your planted tank looks absolutely stunning. Because I will be keeping a couple of Oscars, I'm not sure how well the plants will do. We all know how Oscars like to destroy plants. I will probably give it a go and see what happens anyway.
Like I said, I'm sure you'll have a few tips for me. I run a 125 gallon tank at the moment, that seems very big, until you stand next to the 300 gallon