Trident shows lower dkh than Hanna

[chicago]

so noticed tips alk burn on sps.. but how can that be. Trident shows 7.8. Tested with Hanna and I am at 9.4 ... My tank does better at lower dkh. I have held it for years at around 7.5 to 8. I calibrated the trident twice now and still getting readings of 8.3 or so and the Hanna is at 9.4. I then checked with some other tests and then show 9.5 or even higher.. none showed below 8. Thoughts..
1. bad batch of reagent for the trident ?
2. Trident is right others wrong
3?

 

[cilyjr]

Are you calibrating using your test results or are you using the Trident solution? I always just calibrate according to my trusted test kit.

 

[cilyjr]

I calibrate every month or so and that's been working well for me

 

[Reefer Matt]

When you calibrate, do you put the calibration bottle at the same height the sample line is in normal operation? Also, do you prime the sample line after putting it in the calibration solution, and again after putting it back into the tank?

 

[cilyjr]

do you put the calibration bottle at the same height the sample line is in normal operation?

Out of curiosity, why would that matter?

 

[OctaviusBrine]

I always calibrate with my test kits their solution is always off. Also if the reagent is low I swear it drifts in accuracy. Not all that impressed with my trident. Especially for the money they get for everything.

 

[Reefer Matt]

Out of curiosity, why would that matter?

It matters a lot for proper calibration. The back pressure on the tubing is what affects the calibration. That's why you can't cut the sample or waste lines. Plus, you must prime the calibration solution so it is drawn into the sample line before calibrating. Then you prime again after calibration to make sure the tank water is in the sample tubing.

https://www.neptunesystems.com/getstarted/trident/calibration/

 

[cilyjr]

It matters a lot for proper calibration. The back pressure on the tubing is what affects the calibration. That's why you can't cut the sample or waste lines. Plus, you must prime the calibration solution so it is drawn into the sample line before calibrating. Then you prime again after calibration to make sure the tank water is in the sample tubing.

https://www.neptunesystems.com/getstarted/trident/calibration/

I get the priming, was curious about the height. I suppose it makes sense. Back pressure could affect things somewhat.

Thanks