KH director reading issue

hello hope everyone is doing good
recently bought kh director with a standalone doser I'm continuously having issues related to the reading of khd the reading is not stable and is always on the higher side like 10 khd when I run tests back to back e.g 3 to 4 tests the reading gets lower to what my Hanna checker shows but when after when it's doing routine test the khd again goes back to the higher side I have tried 7.5 sample water but still no luck in collaborating the device
need expert help because I can not rely on kh measurements of kh director

Hello,

I'm sorry you're having trouble with your KH Director. Have you consulted our knowledge base, in particular this article:

https://www.aquariumcomputer.com/kno...oubleshooting/

And also https://www.aquariumcomputer.com/kno...e-kh-director/

Gaël

First thing I would do is make sure your water sample is correct. Forget the calculator actually do a test on how much water is actually in tube and use a scale put that number in sample tube volume. After that calibrate that pump again using a scale make sure no air bubbles; I use a little weight to put tube down further in sump. After calibration make sure no water in tube left; go onto the reagent pump next this one make sure no air in it you can vent this as well to be sure. the vent tube must not be in contact with water (the tube in back of KH director). Calibrate all the remaining pumps again using a scale. make sure no fluid is left in pumps except the one with reagent usually pump 2. After that flush measurement cell make sure absolutely no leaks where the probe goes in if not proceed with test.

I would get reagent reference fluid run 3 tests back to back. When you do this test make sure before test you flush out measurement cell first then flush measurement cell using the reference solution. You should get the same results 3 times after that you can adjust the KH director using the formula. (7.5 – KHD value) / KHD value = Percentage adjustment

the links above may help as well again the most important is the water sample size and calibration of the pumps.