100 off is unacceptable.
100 off is unacceptable, but I think there is still a question of exactly what is inaccurate here. It’s possible that the trident is wrong and it’s possible that the other test kit is wrong. It’s also possible that they are both wrong and the actual value is somewhere in the middle.
The unknown is what’s so difficult here. Hobby grade test kits aren’t known for their accuracy and as one person stated above, trying to get everything to match is just going to drive you mad.
At the end of the day stability matters more than a specific number. As long as whatever test you choose to use provides consistent and reliable results you’ll be successful with your tank.