Very important!

We didn't mention this in the manual (we just didn't think that this will be made wrong), but it happened already a few times and caused wrong measurment results.

The KHD ventilation/overflow tube (from rear connector) must NOT end below the water surface of your waste water - it must be hanging free ABOVE the water surface, it MUST not be possible to suck water into it!

We will add this to the instructions ASAP.