I'm doing a flat bottom (no sloping) carpet plant only tank over a 18x30" bottom, with all fish well under an inch long (no diggers or pickers). The carpet will primarily be Elatine triandra and flat clumps of Rotala Goias. Root wise, I know I can get away with a 1.25"-1.50" bottom, but do you still think I need at least 2.0" to enjoy a healthy mulm population? I will also have a xP3 canister filter with 3 liters of porous mulm growing medium. I'm using a coarse sand/fine gravel called "peace river" from Caribsea which is heavy, spherical and is limited to a 1-2mm grain size.