Currently I am using Salifert for nitrate, cal, alk, and mag. I don't test for anything else. My experience with api is that the cal seems to jive with salifert, nitrate has given me some false negatives (it could be me I suppose), one test would show 0 nitrates and the next test from the same sample might show 20ppm nitrates. When I used api I would always test twice.

My next kits will be Lamotte for cal and alk. I will probably stick with Salifert for nitrate and mag.

I set up a nitrate test with Ocean, Tetra, Salifert and API. The discrepency in readings was scary to say the least. I have never seen the Ocean nitrate test show ANY nitrates despite readings by every other kit.