diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index 6968534..7e45f14 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -24,6 +24,7 @@ namespace sensor {
   int16_t stable_measurements = 0;
   uint32_t waiting_color = color::blue;
   bool should_calibrate = false;
+  unsigned long time_calaibration_started = millis();
 
   void initialize() {
 #if defined(ESP8266)
@@ -100,10 +101,11 @@ namespace sensor {
      * a measurement rate of 2s for at least two minutes before applying the FRC command and sending the reference value.
      */
     Serial.println(F("Setting SCD30 timestep to 2s, prior to calibration."));
-    scd30.setMeasurementInterval(2); // [s] The change will only take effect after next measurement.
+    scd30.setMeasurementInterval(MEASUREMENT_TIMESTEP); // [s] The change will only take effect after next measurement.
     Serial.println(F("Waiting until the measurements are stable for at least 2 minutes."));
     Serial.println(F("It could take a very long time."));
     should_calibrate = true;
+    time_calaibration_started = millis();
   }
 
   void calibrateAndRestart() {
@@ -126,18 +128,22 @@ namespace sensor {
   }
 
   void displayCO2OnLedRing() {
-    if (co2 < 250) {
+    int16_t co2_int = co2;
+    if (co2_int < CALIBRATE_LEVEL) {
       // Sensor should be calibrated.
       led_effects::showWaitingLED(color::magenta);
       return;
     }
+    if(co2_int < 400) {
+      co2_int = 400;
+    }
     /**
      * Display data, even if it's "old" (with breathing).
      * Those effects include a short delay.
      */
-    if (co2 < 2000) {
-      led_effects::displayCO2color(co2);
-      led_effects::breathe(co2);
+    if (co2_int < 2000) {
+      led_effects::displayCO2color(co2_int);
+      led_effects::breathe(co2_int);
     } else {
       // >= 2000: entire ring blinks red
       led_effects::redAlert();
@@ -170,7 +176,10 @@ namespace sensor {
      */
     if (freshData) {
       if (should_calibrate) {
-        countStableMeasurements();
+        if(millis() - time_calaibration_started > 60000)
+        {
+          countStableMeasurements();
+        }
       }
       logToSerial();
     }
diff --git a/ampel-firmware/config.public.h b/ampel-firmware/config.public.h
index ef04315..4f6d153 100644
--- a/ampel-firmware/config.public.h
+++ b/ampel-firmware/config.public.h
@@ -5,6 +5,10 @@
 #define buttonPin 0
 // This file is a config template, and can be copied to config.h. Please don't save any important password in this template.
 
+// This is the level at which the magenta LED color signals need for calibration
+// in some case it is irritating when this happens so you can lower this level if need - but use with care. Calibration shuld be done time to time
+#define CALIBRATE_LEVEL 250
+
 /**
  * SERVICES
  */
@@ -12,11 +16,10 @@
 // Comment or remove those lines if you want to disable the corresponding services
 // #  define AMPEL_WIFI    // Should ESP connect to WiFi? It allows the Ampel to get time from an NTP server.
 // #  define AMPEL_HTTP    // Should HTTP web server be started? (AMPEL_WIFI should be enabled too)
-// #  define AMPEL_MQTT    // Should data be sent over MQTT? (AMPEL_WIFI should be enabled too)
+//#  define AMPEL_MQTT    // Should data be sent over MQTT? (AMPEL_WIFI should be enabled too)
 // #  define AMPEL_CSV     // Should data be logged as CSV, on the ESP flash memory?
 // #  define AMPEL_LORAWAN // Should data be sent over LoRaWAN? (Requires ESP32 + LoRa modem, and "MCCI LoRaWAN LMIC library")
 
-
 /**
  * WIFI
  */
@@ -31,7 +34,7 @@
 
 // How often should measurement be performed, and displayed?
 //NOTE: SCD30 timer does not seem to be very precise. Variations may occur.
-#  define MEASUREMENT_TIMESTEP 10 // [s] Value between 2 and 1800 (range for SCD30 sensor)
+#  define MEASUREMENT_TIMESTEP 2 // [s] Value between 2 and 1800 (range for SCD30 sensor)
 
 // How often should measurements be appended to CSV ?
 // Probably a good idea to use a multiple of MEASUREMENT_TIMESTEP, so that averages can be calculated
@@ -41,17 +44,17 @@
 
 // Residual heat from CO2 sensor seems to be high enough to change the temperature reading. How much should it be offset?
 // NOTE: Sign isn't relevant. The returned temperature will always be shifted down.
-#  define TEMPERATURE_OFFSET -3 // [K]
+#  define TEMPERATURE_OFFSET 0 // [K]
 
 // Altitude above sea level
 // Used for CO2 calibration
 // here: Stuttgart, Schellingstr. 24. (Source: Google Earth)
-#  define ALTITUDE_ABOVE_SEA_LEVEL 680 // [m]
+#  define ALTITUDE_ABOVE_SEA_LEVEL 660 // [m]
 
 // The reference CO2 concentration has to be within the range 400 ppm ≤ cref(CO2) ≤ 2000 ppm.
 // Used for CO2 calibration
 // here : measured concentration in Stuttgart
-#  define ATMOSPHERIC_CO2_CONCENTRATION 425 // [ppm]
+#  define ATMOSPHERIC_CO2_CONCENTRATION 430 // [ppm]
 
 // Should the sensor try to calibrate itself?
 // Sensirion recommends 7 days of continuous readings with at least 1 hour a day of 'fresh air' for self-calibration to complete.