For those who havn't read these yet, I thought I'd post links to articles on a couple of sand bed experiments done by Rob Toonen and Christopher Wee
An Experimental Comparison of Sandbed and Plenum-Based Systems. Part 1: Controlled lab dosing experiments
An Experimental Comparison of Sandbed and Plenum-Based Systems: Part 2: Live Animal Experiments
It's interesing that the sandbeds processed nitrates equally regardless of their depth (no anaerobic zone), and particlle size.
Bare bottom tanks were not included in the experiments, but I don't think we need to guess how much nutrient a bare tank would process
