Best Method of reducing nitrates, without affecting minerals and other nutrients.

[Byron]

Ah thank you, it was a low tech tank, but about 4 months ago I decided to include more plants and upgraded to a high tech tank, so its running on Tri-Spec 2 lights, and co2 injection. I provide root tabs, and some liquid fertiliser (Seachem Iron, Potassium and Phosphorus). But mostly just root tabs, and since my water is hard no minerals are added.

That makes a difference. Though it still depends upon the amount of ammonia/ammonium generated by the fish, decomposition of organics, etc. If this is sufficient to balance the light and other nutrients, that is all you would need. It really is amazing how much ammonia/ammonium fast-growing plants can assimilate, and they are faster at doing it than the nitrifying bacteria.