Sulfur Denitrator ORP, Flow, Affluent question

[Exus]

So I'm dialing in a new Sulfur Denitrator, about 2 months, I'm come across a werid intersection.

I've heard that you shouldn't let ORP get below -300, and that the best range for it is -50 to -150.

I'm current at -26 ORP and the nitrates in my affluent is still 0ppm at 55ml/min flow. Based on the instructions, I should be increasing flow until I get a non-zero result, but if I increase flow by just 5ml/min, the ORP goes to the positive range. The actual nitrate of the 150gal tank seems to be stable around 10-15ppm over the past week or so at the 55ml/min flow, and I'm fine with it staying at this range.

Should I do anything? I feel that I should just leave it as is. Or should I keep increasing flow even if it results in a positive ORP.

 

[Randy Holmes-Farley Verified Community Expert]

Is tank nitrate declining day to day?

 

[Exus]

Is tank nitrate declining day to day?

I just tested again now, and it's at 8.7 Nitrate and 0.0 Nitrate Effluent. I tested 4 days ago and it was at 14. 4 Nitrate. But it has ranged up and down over the past couple of weeks around there.

 

[xzt]

I think that as long as the nitrate concentration in your reactor's effluent is 0, you can slightly increase the flow rate. In my use, my only concern is the production of hydrogen sulfide, which is toxic, so I additionally monitor the hydrogen sulfide level in the effluent. Initially, because the water inside the reactor was not mixed evenly, local dead zones formed, leading to hydrogen sulfide generation. Later, I resolved this issue by enhancing the water flow within the reactor.

 

[Exus]

I think that as long as the nitrate concentration in your reactor's effluent is 0, you can slightly increase the flow rate. In my use, my only concern is the production of hydrogen sulfide, which is toxic, so I additionally monitor the hydrogen sulfide level in the effluent. Initially, because the water inside the reactor was not mixed evenly, local dead zones formed, leading to hydrogen sulfide generation. Later, I resolved this issue by enhancing the water flow within the reactor.

I have the GEO's reef sulfur denitrator, and it has a recirculating pump. And the Effluent doesn't have any bad smell to it. I'm worried if the ORP gets too high, it might end up killing the anaerobic bacteria. I'll try increasing by 2.5ml/min every few days to see.

 

[Randy Holmes-Farley Verified Community Expert]

I just tested again now, and it's at 8.7 Nitrate and 0.0 Nitrate Effluent. I tested 4 days ago and it was at 14. 4 Nitrate. But it has ranged up and down over the past couple of weeks around there.

I personally would not want it using up more nitrate since it looks like its on a fast path to levels below my target range.

 

[czynot]

You dont really need orp probe. You keep increasing your effluent until the effluent coming out show slight amount of nitrate. You will smell rotten egg if your effluent is too slow.
Beware of lower ph in your tank when running sulfur reactor. Also bacteria in the reactor consume alkalinity BUT NOT calcium. Your Calcium will slowly creep up over time.