Thank you for the information. How would it be possible for nitrite to be showing up a year and a half in with a tank?Without a confirmation that nitrite is zero, or almost zero, most nitrate tests used will give false high nitrate reading. Seems odd that removing macro, which uses ammonia directly, would give an instant nitrate high. This could be accounted for by a nitrite reading (probably not harmful) which is then multiplied by a massive amount (sometimes x100) in the nitrate test.