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Old 11/16/2007, 05:52 AM
mxett mxett is offline
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Join Date: Jun 2007
Location: Melbourne Australia
Posts: 224
Agree with IPT. The idea of a dsb is to have anoxic sand in the areas below 4 inches or so. Then the nitrate seeps very slowly into these regions via diffusion, and the anoxic bacteria complete the nitrogen cycle by 'processing' the nitrate into nitrogen gas. Having any water flow THROUGH the sand bed will create an oxygenated sand bed which will not process nitrate.