Sulfur denitrator experiment

[Psyire]

Your last 2 points revolve around a 1-pass reactor if I'm not mistaken. I don't believe T.R.A. Vol.3 discusses recirculating reactors. (therefore volumes and flow rates are changed)

I wouldn't increase the flowthrough rate of the recirc. chamber if I were you. This will nullify the 'O2-Free' zone if the flow is too much.

You may want to check your test kits as stated above, just in case something is off. I would just run a nitrate test on your new makeup water, during your next water change to see what it reads.