I have been using the tetra nitrate and nitrite testing kits and now my readings have started to drop. I have been doing daily 20-30% water change for what seems like forever ( originally used the 5 in 1 test sticks and that showed a high reading). Ammonia has always been clear. While putting the stuff back in their boxes I began reading the back . Todays read as NO2 0.3 mg/l and NO3 as 12.5mg/l( originally NO2 1.6 mg/l and NO3 50mg/l). The back of the box says for No2 to divide the reading by 3.3 to get the Nitrite/nitrogen mg/l and NO3 to divide it by 4.4 for nitrate/nitrogen mg/l) I have never understood chemistry( except when it comes to cooking!) but what reading am I looking for?