The only one you have to increase is the phosphate. Nitrates and phosphates should be in a 10-1 ratio. So if nitrates are 10 ppm
then phosphate should be 1 ppm
. If nitrates are 20 ppm
, then phosphates should be 2 ppm
and so on. The iron and potassium should be dosed based on the water volume and not the nitrate amount.
What do you think is causing your high nitrate level? Water changes once a week, correct nitrate dosing, correct stocking levels, and a moderately planted tank should eliminate high nitrate levels.