Dose For High Fish Load

I can't figure this out, but even after my weekly water change, my Nitrate measurements are about 15 - 20 ppm BEFORE I dose EI. I have a 150 gal tank that is fairly heavily planted and 3.2 WPG for PC lights. I never seen to uptake Nitrate OR the fish are adding as much as the plants are consuming. I have about 55 fish in this tank. I do not over feed them. They are mostly African Cichlids (Tanganyikans) and 10 fat SAEs.

I have been a little concerned that with Nitrates consistentlt greater than 25 ppm, I'm asking for trouble so here's the question.

How much do you think I should dose and of what to get the required P and K without dosing KNO3 for N? I have a bottle of Flourish Potassium I could use for that, but what do you think in general. My typical reset dose using EI is:

1.5 tsp KNO3
1/4 tsp K2HPO4
1 tsp K2SO4

Any ideas?

Thanks,

Mike

Re: Dose For High Fish Load

Thanks Ian. That's what I kind of thought. I think what I'll try to do is Measur ethe Nitrates daily this week and adjust my reset dosage next week. Funny thing too, I just tested my tap water and Nitrate was measurable (Salifert test kit 3-5 ppm).