Tony answered the above questions well, but I can definately add some info regarding ORP.
The denitrification process taking place in the sulphur media is one of reduction and requires an anerobic condition. An ORP value of -50 to -300 is perfect for the stabilization of these anerobic bacteria. Higher than -50 and you get too much oxidization or oxygen present, and lower than -300 and you get a byproduct of Hydrogen sulfide. (H2S) The ORP probe is in there to monitor ORP so I am better able to adjust my 'flow, or drip rate' through the reactor. This will inable me to have the best possible environment for these anerobic bacteria at all times. Atleast that is the theory behind it...
|