Does anyone else have problems with the API nitrate test from the master test kit? My nitrate test always seems to be either 40ppm or 80ppm. Yes, I do bang the 2nd bottle well, give it a good shake. I ran a separate test using a Tetra liquid test and it seemed to show around 25ppm. Now I know that a lot of people agree API is one of the better test kits but I'm having this annoyance. I also tested my tap water and had the same readings. A thoughts on this or alternative tests for nitrates would be great. I the mean time I'm hoping my new water wisteria grows quickly and starts sucking some of that nitrate up.