KH Director reading too high - tried a lot of the known fixes

[Bob_The_Reefer]

Vinny posted this

Hello Oscar,

The correct tolerance when using the KHD and Reference solution is +/- 0.4° dkH (0.2 from KHD and 0.2 from Reference solution).
Given your results, you are within the tolerance range.

If you would like to get the KHD result a bit closer to the 7.5 mark, check again your tube lengths and calibrate your pump heads. When calibrating pump heads, you can use a digital scale to get the most precise measurement; 1g = 1mL

You can also verify your water sample tube volume by temporarily disconnecting the tube going into the KHD and manually filling both ends of the tube. Empty this tube into a digital scale or measuring cup and type-in the amount into the tube volume field in the KHD settings page.

In addition to putting the filter at the end of the sample tube I found tiewrapping the filter in a 25mm pvc tee helped the consistency (and kept the filter where I wanted it)