I dose using the pps-pro method. I noticed that my P and K was low so I started to dosing extra P and K. So far so good!
I do a weekly water change of about 50%, maybe a little less. My nitrates are about 10ppm after the change. Then about midweek they are around 40ppm( i guess, its hard to tell for sure with the color chart). I do have a heavy fish load.
So this is my thought, I would stop dosing N..but continue the daily P,K,Mg and micros, with extra iron 2x a week.