New-ish Trident user here. I bought a 6-month batch of reagents and eventually noticed the calibration liquid. I didn't use it initially because I wasn't paying close attention...I used Hanna and SF tests for Alk, Ca, and Mag, and then I did my calibration. Things were looking good, but then I noticed the calibration bottle. Thinking I messed up, I did the calibration with the bottle, followed by a test afterward, and it was way off from the last Trident result, which was 3 hours previously.
I did another manual test and confirmed that the calibration bottle had messed up my test results. I re-calibrated with my manual tests, and all seemed well. Five days later, I did another manual test to compare to how my Trident was testing, and it was almost spot-on.
In short, I agree that the calibration liquid is trash. A local fragger who works from his house also said he never trusts them because when he got his first Trident, it was always off until he re-calibrated it to his manual tests.