I have been reading this thread and would like to comment.
I've been fighting nitrates and my attempts to date have not been highly successful.
djbon's apparatus differs from other denitrifying set ups like coil denitrators and the deltec NPF 509 in that he is running much larger volumes through the device.
Coil denitrators are typically run at a few drops per second (which is why they don't work- they don't turn over the volume fast enough to lower nitrates).
The Deltec NPF 509 instructions start by dosing carbon for three days without running the device, then starting at 1 drip per 3 seconds, then increase by 20% per few days. Eventually over weeks if not months, getting to turning over the tank ever 14-28 days.
Djbon starts his reactor immediately at a flow of ml/second vs drops per second.
The idea of the coil and deltec reactors is to create an anaerobic environment (in the coil case, by removing O2 in the coil and processing nitrogen in the chamber, and it the deltec, to circulate the water so that the whole chamber is anerobic.
I don' t think this can be happening in the djbon reactor. Flow is too high. Rather I think what is going on is that flow is slow enough that the distal portions are low in O2,
AND it is only inside the media that anaerobic conditions are taking place.
So, I think the key to understanding and reproducing djbon's success is understanding the media he is using. My guess would be that the only effective media in the reactor for nitrate reduction are the largest pieces that have a core that can be anaerobic.
I have not had success using small pieces of media in the reactor. I am thinking that large pieces of pumice and other porous subrates are key to this reactor working.
