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Level Control and Leakage Monitoring

Level control with the ProfiLux

ProfiLux 4(e) can regulate the water level (= level) in various ways.

ProfiLux 4(e) has 4 inputs for level and leakage detectors and can optionally control 12 inputs. In addition to level sensors, you need additional accessories (for example, Expansion cards with level inputs or an Expansion Box 2) for full use of the 12 independent level controls

Why is level control with ProfiLux so safe?

Since the level control is a sensitive matter, various safety precautions have been taken.

  1. Our sensors and the evaluation electronics are designed in such a way that a withdrawal of the sensor plug or a cable break is interpreted as reaching the desired level and the corresponding socket is switched off.
  2. In addition to the more cost-effective mechanical float operated sensors, we also offer optical or contact-less sensors (without mechanical parts). These cannot get stuck in a position due to contamination.
  3. Furthermore, time limits are adjustable which limits the switching duration of the sockets. Thereby, overflow due to a defect can be prevented in most cases

What level control modes are provided?

Depending on whether you use one or two sensors, different operating modes are available:

Operation modes with 1 sensor:

-> Auto-top-off (ATO) (1 sensor)

As soon as the sensor registers a low water level, the switch box with the function Fill water is switched on. When the nominal level is reached, it is switched off again.

Then you can set if the auto top off shall be always active: ATO always? If not, then you can afterwards select a timer. In this case, the selected timer defines when the ATO may be active for this sensor.

-> Leakage detection (1 sensor)

If the sensor is activated, ProfiLux 4 assumes a leakage and triggers an alarm. As long as there is no alarm, the switchable socket with function Fill water is switched on, in case of an alarm switched off.

-> Return pump (1 sensor)

As soon as the sensor registers a high level, the switchable socket with the function Water fill is switched on. When the level falls below, it is switched off again.

Operation modes with 2 sensors:

-> Water change (2 sensors)

For adjustable times the water is drained off (switchable socket with function Water drain is then switched on) until sensor 2 signals the minimum water level. After this, Water drain is switched off and the socket Fill water is switched on until the water reaches sensor 1.

-> Sensor 1 signals, that the tank is full again, sensor 2 indicates when enough water has drained off. Switchable socket Fill water switches freshwater supply, Drain water switches the outflow.

After the selection of this operational mode, the timer has to be selected which shall define the time of the water change. Please don’t forget to program the selected timer accordingly afterwards (set here switching period to Event start, see also Clock-> Timers).

->Timers). The water change is then started at the times set there.

-> Water change and ATO

Like Water change, additionally socket Fill water and level sensor 1 serve as ATO if there is no water change running at that time.

-> Min/Max control

Two sensors work together to control a water level. Sensor 1 works as a maximum-switch, sensor 2 as a minimum-switch. As soon as sensor 2 registers a too low level, the switchable socket with function Fill water is switched on. When the water level reaches then sensor 1, the switchable socket is switched off again.

-> ATO 2 sensors

Like ATO, but 2 sensors are used to register the same level. Only if both sensors register at the same time a too low level, the switchable socket with function Fill water is activated. So this function offers additional safety.

Maximum on-time

Due to safety reasons you can set how long the switchable sockets with the functions Fill water and Drain water may be active at maximum. 8 hours can be set at maximum.

Through this, you can avoid that a defective sensor leads to a (too big) flooding. In case the time is exceeded, the level control and the related switchable sockets are immediately deactivated and an alarm is triggered! The level control remains deactivated as long as the error is reset or the ProfiLux 4 is restarted.

If here 0 is set as duration, then the time monitoring is deactivated.

For a switchable socket which is assigned to a control with the function Leakage detection there is no monitoring of the maximum switching time.

For an automatic water change this Maximum on-time is valid for both sockets (drain and fill).

A restart of the ProfiLux 4 (also after a power-cut) resets the error and the time monitoring will be restarted.

Automatic Error reset

If you confirm “Reset Error?” with Yes then errors for this control will be reset automatically as soon as the sensor signals no (or again) water contact (depends on the operation mode).

This function offers a higher degree of convenience because in case of the Automatic Top Off, an error is automatically reset as soon as the missing water is re-filled manually. It does however, carry a higher risk since the cause of error could persist further on. Therefore we recommend full consideration if this function is to be used.

Sensor select

Here, you can determine which level sensor inputs are to be used by this level control.

2 sensors are to be selected for operating modes with 2 sensors.

After setting the level control (function), please assign the sockets (hardware) to be switched by the level control, see also under System-> Socket outlet function.

If you are not familiar yet with the operating concept of the ProfiLux Controller, we highly recommend to first read the Knowledgebase Article “How the ProfiLux Controller works“.

It  gives you an understanding of the basics and the operational concept of the controller.


After selecting a level sensor input, you can set its behavior. Normally these settings need not be changed.

-> Reaction time

Set here the Reaction time of the level sensor input. It can be set between 0s and 240s (Standard is 1s).

This feature is useful in instances where you may want to set a level sensor reaction delay. In areas where there is frequent water surface agitation in the same area as the sensor, the assigned switchable socket may turn on/off too often. ProfiLux 4 monitors if the signal (= water there/not there) transmitted by the sensor is stable.

Stable means in this case that a change of the level has to remain constant at least for the set reaction time. Only if the level is stable, the level control reacts.


The Reaction time should be set high enough so that waves do not cause a response of the control, but also small enough so that an attained level is not detected too late.

-> Input inverse

Under certain circumstances it may be useful to invert the switching behavior of the sensor (for example, if the sensor can only be installed upside down). Confirm Input invert? with Yes then the sensor input is inverted.

Error reset

If there is a timeout/overrun (socket with function Water switched on too long, see also under Maximum switching duration) or the leakage monitoring system triggers an alarm, the error status in the device must be reset. This also resets the alarm.

As long as the error has not been reset, the level control remains inactive.


To facilitate the implementing of the level sensors, the menu item Diagnostic is available. The current state of all level sensor inputs is displayed here. On contact with water (= sensor active) the corresponding number of the sensor input is displayed.

The display of “1   4   8” means that sensor inputs 1, 4 and 8 signal contact with water.

The diagnosis is terminated with Esc

Please note that a “contact with water” is also displayed when no sensor is connected.

Start Water Change

For all level sensor controls with the operating mode Water change or Water change & ATO, you can start the automatic water change manually here. After you have answered safety question with Yes, the water change starts.