What I meant by your water quality is that when you first posted your
NH3 and
NO3 were a little elevated, the
NH3 is bad in any amount and
NO3 is generally suggested to be kept at 0- 20ppm with 40ppm and above becoming stressfull.
If your finished with meds as directed then I would stop treatment, add fresh carbon to remove meds, continue with
PWC's as needed to maintain water chemistry/quality and once all the meds are cleared (24hrs with good carbon) add some Melafix and/or Pimafix and a little salt. Remember you'll need to remove the carbon again and follow directions when using Mela/Pimafix.
Disclaimer; these are my recommendations, this is the course of action I personally would take, others may suggest alternative forms of treatment.
You could do everything right and still lose a fish.
The lack of outside stress from outside the tank is a good thing, and so is keeping the lights off, all postives for your fishes recovery.
You will need to continue to closely monitor your water chemistry as you may experience a cycle, whether its a mini or full will depend on "If" or "How much" the meds affected your cycle.
Its good that your acquiring a
NO2 test, you will need to test
NH3,
NO2 and
NO3 if you do experience a cycle.
You can add your Hornwort whenever, I do not believe that Mela/Pimafix has any effect on live plants.