More water chemistry

I did a major water change. Several of the female platies were looking very unhappy, so I decided to try a major water change. I changed about 12.5 gallons, probably about 25% of the total water in the tank. I managed to bring the NO₂^- levels down to between 1 and 3 ppm, down from the "danger" zone to the "stress" zone. Obviously I lowered the NO₃^- level as well - nothing I could do about that. Hopefully the plants won't mind too much - after all, from what I have read, Fe is the major limiting nutrient.