Update.
Flowing 20 GPD. 0 ppm nitrates. Tank is still above 20 ppm.
Had to calibrate the ORP meter, as my old 0 ppm mv reading still had some nitrates,
My ORP probe is old and is only accurate as calibrated to a known value. Or perhaps the distilled water I added a few weeks ago tweaked it.
To calibrate it I just do hourly nitrate test as the mv numbers increase, when 0 ppm tests. That becomes the new bench mark. It was -2mv now it's + 5 mv. The ORP mv reading is very sensative to tiny changes.
Flowing 20 GPD. 0 ppm nitrates. Tank is still above 20 ppm.
Had to calibrate the ORP meter, as my old 0 ppm mv reading still had some nitrates,
My ORP probe is old and is only accurate as calibrated to a known value. Or perhaps the distilled water I added a few weeks ago tweaked it.
To calibrate it I just do hourly nitrate test as the mv numbers increase, when 0 ppm tests. That becomes the new bench mark. It was -2mv now it's + 5 mv. The ORP mv reading is very sensative to tiny changes.