reverse-flow RDSB

[antiant]

i was planning to set up a reverse flow RDSB in a separate container in my sump. the water will be pumped through the bottom of the container and controlled with a ball valve. are there any problems with this design? please let me know, as this is just an idea i got. thanks.

[IPT]

I don't think it'll work. If I understand correctly the DSB functions because it is so deep there is a lack of oxygen in the lower layers. The water merely flows over the top of it. By pumping water up thru the sand you'll introduce oxygen to the deeper layers of it and you will not get the denitrification. Maybe someone can conform this, but that's what I recall reading in some posts from Anthony Calfo.

[mxett]

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.

[antiant]

thanks. good thing I asked first.