so your just going to fill the mid section with plantlife?

Seems like that would work as good if not better then the regualar mixture of balls and sponges. Only thing that comes to mind is the decaying plant life. You could try to put a screen above that last wall to catch the debris before it gets to the powerhead

the water lettuce, imo, will get everywhere however, it doest need any substrate. which is what you want. but i find that they discart alot of roots. i have a bamboo bowl (2ft dia) with them. i tried puttign them in a tank before and i was constantly picking roots out of the tank, and i only put one ...cluster... of them. Secondly, and limp leaves or leaves catching a splash will leach the tank lowering the quality, as im sure you know. Id go with the wart, and if you don;t want rock, root them in some biosponge and then you can easily remove them in a bulk and clean the sponge and replace it


Where you plan on putting this sump?

gotta admit that white caulking is ghastly.


THis is a great idea.