KH Director new setup help

I am trying to setup a new KH Director unit. After working on it for the past couple of days, I am able to get it running on a stable basis. However the KH measurement is showing up in 11+ whereas my Hanna meter shows around 8+. I ran the measurements multiple times back to back it is showing 11.4, 11.6 etc. which means that the KH director itself is working fine. I am trying to eliminate few other factors that might affect the measurement.

I measured the tube from the sump to the doser and it is coming to 66.5". Add 4.2" of silicone tubing in the doser and another 6.3" of tubing that goes from doser to director, it gives me a total of 77". If I enter this it gives me 24ml of sample water. This is what I used for few tests. Then I separately measured the water from the tube for the entire length using a graduated cylinder which showed me there was a total of 21ml of sample water in the tube. I tried both numbers and the difference in KH is not much different. They are still in 11ish range.

The other thing I noticed is the pump that pulls reagent stops in between for a brief moment as it pulls the reagent. See here for a video https://www.youtube.com/watch?v=auqnxo1glP8.

Is this normal?

I took the electrode out and tested by placing them in 4 and 7 reference solution and they are within acceptable range. So I ruled that one out.

What else should I be looking for to get an accurate KH result?

Here is another video. Stop and go stop and go. Is this normal? Also this time I cut the reagent tube shorter and moved the bottle closer.
https://youtu.be/LGg6sjMBRUc

Since I moved the reagent bottle closer, I re-calibrated the pump. Now the Kh is at 10. Better than before. Still doesnt match with what Hanna is showing which is 8.51. I understand these dont need to match but I want to know if there is any other setting I should be looking into that can get the KH much more accuarate.

Hi there,

Since the KHD is providing consistent values and you've already checked the pH probe, that means everything on the unit itself is working properly which is great! Having also checked and verified the sample tube volume further shows the device is providing reasonable values. That leaves us with looking at the Hanna checker itself...

These instruments have been found to provide different values with each test being heavily dependent on the age of the reagent powder. We've written an article which discusses the cause of these differences. You can find that here, if you're interested:
https://www.aquariumcomputer.com/kno...oubleshooting/

The best way to fine-tune your KHD would be to run a few tests using the 7.5dkH Reference Solution. This will be far more accurate than traditional kits as it rules out the common variables of dust, fingerprints, sample size interpretation, etc. You also have an adjustment tool in the KHD settings which lets you adjust the KHD's end result to match that of the reference solution if need be.

hi Vinny, thanks for the response. I did an API test last week. It showed 7.92. Same day Hanna test showed 7.22. So I think Hanna is closer than that KHD is showing. Can I adjust it in KHD setting or do you believe running few tests in 7.5dkh reference solution will benefit in any way?

Using the reference solution will rule out any factors introduced by the API and Hanna kits.

If you want to adjust the readings, go to the KHD settings page and at the top of the page you will see the adjustment option.