I have been running an Apex Trident is 2 tanks (a 150 gall and 45 gallon both reef tanks). Over the years, I have run into issues and used the APEX change out program a few times. Recently, I noticed that my ALK has been reading low on both tridents. I have used the calibration a number of times and have always wondered about the instructions. You have to input the reading that are on the bottle into fusion and let the trident run the calibration for about an hour. Numbers always come up the same that are on the botltle. After the calibration, I run a combine test and the the numbers are off. I test my water using 3 test kits (Hanna, Red Sea and API) generally all 3 tests come in close but the trident is never close to any of the 3 tests. When calibrating, it almost seems like you are forcing the numbers to read whats on the bottle. It would seem more efficent if you ran a combined test just using the fluid from the bottle and see what the results are. Does anyone have any thoughts or maybe tried doing this?