Placement of KH Director and Doser 2.1

[NorwayEagle]

Good morning.

I am in the evaluation phase of investing in KH control equipment, and reflect on the KH Director or the Alkatronic.
Due to limited space, I have to place the unit inside my cabinet below tank, and one reason to look at KH Director is the following (I hope) possibility:.

Is it OK to place the KH Director and the Doser 2.1 vertically, or must they be placed horisontally as described in manual.

What is the argument for horisontal placement, are there any limitations I do not see?