Aqua Bathroom Conditioner (Low Pressure) : 3/4'' Pipe Fiting for 1-3 Bar Pressure
If you want your apartment bathtub to be free of soap-scum, we recommend you to get an Aqua water softener for Bathrooms. It can be installed in the water supply line of your individual Bathrooms
 
If each bathroom has a single line you can install Aqua Bathroom-1 (AC9) inline onto the inlet of your bathroom
If you have a common line that further separates into two lines entering your bathrooms you can install Aqua Bathroom-2 (AC12) on the common inlet. (High Pressure)
If you are not sure about your flow-rate we recommend installing a small in-line booster pump right before the unit to get the desired results.