A trick with Tridents: use the sample water in your tank and calibrate manually based on your test results (and not the calibration solution Neptune provides).
2 months since last Trident check:
* Alkalinity | Hanna: 8.24 dKH ... Trident: 8.31 dKH
* Calcium | Hanna: 504ppm ... Trident: 496ppm
* Magnesium | AF: 1460ppm ... Trident: 1455ppm
2 months since last Trident check:
* Alkalinity | Hanna: 8.24 dKH ... Trident: 8.31 dKH
* Calcium | Hanna: 504ppm ... Trident: 496ppm
* Magnesium | AF: 1460ppm ... Trident: 1455ppm