diff --git a/gui/main.py b/gui/main.py
index 05ad131..df67f9f 100644
--- a/gui/main.py
+++ b/gui/main.py
@@ -52,9 +52,15 @@ class PHControllerGUI(QMainWindow):
         self.flow_rate_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
         self.flow_rate_label.setVisible(False)  # Initially hidden
         
+        self.total_volume_label = QLabel("Gesamt: 0.0 ml")
+        self.total_volume_label.setFont(QFont('Arial', 12))
+        self.total_volume_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        self.total_volume_label.setVisible(False)  # Initially hidden
+        
         status_layout.addWidget(self.ph_label)
         status_layout.addWidget(self.pump_status)
         status_layout.addWidget(self.flow_rate_label)
+        status_layout.addWidget(self.total_volume_label)
         status_group.setLayout(status_layout)
         
         # Control Group
@@ -147,6 +153,10 @@ class PHControllerGUI(QMainWindow):
         # Track pump state
         self.pump_is_running = False
         
+        # Volume tracking
+        self.total_volume = 0.0  # Total volume pumped in ml
+        self.last_flow_rate = 0.0  # Last known flow rate
+        
         # Enable/disable controls based on connection
         self.set_controls_enabled(False)
     
@@ -205,7 +215,10 @@ class PHControllerGUI(QMainWindow):
         self.ph_label.setText("pH: --")
         self.pump_status.setText("Pumpe: --")
         self.flow_rate_label.setVisible(False)
+        self.total_volume_label.setVisible(False)
         self.pump_is_running = False
+        self.total_volume = 0.0
+        self.last_flow_rate = 0.0
     
     def set_controls_enabled(self, enabled):
         self.pump_on_btn.setEnabled(enabled)
@@ -246,26 +259,40 @@ class PHControllerGUI(QMainWindow):
         if self.serial_connection and self.serial_connection.is_open and self.pump_is_running:
             self.send_command("<18>")  # Request current flow rate
 
+    def update_total_volume(self, flow_rate):
+        """Update the total volume based on current flow rate"""
+        if self.pump_is_running:
+            # Add volume from the last second (flow_rate is ml/sec)
+            self.total_volume += flow_rate * 1.0  # 1 second interval
+            self.total_volume_label.setText(f"Gesamt: {self.total_volume:.2f} ml")
+        self.last_flow_rate = flow_rate
+
     def send_pump_command(self, state):
         if state == 1:
             self.send_command("<11>")  # Pump on
             self.pump_status.setText("Pumpe: Ein")
             self.pump_is_running = True
             self.flow_rate_label.setVisible(True)
+            self.total_volume_label.setVisible(True)
+            
+            # Reset volume counter and start timing
+            self.total_volume = 0.0
+            self.total_volume_label.setText("Gesamt: 0.0 ml")
+            
             self.flow_rate_timer.start(1000)  # Request flow rate every second
         else:
             self.send_command("<12>")  # Pump off
             self.pump_status.setText("Pumpe: Aus")
             self.pump_is_running = False
             self.flow_rate_label.setVisible(False)
+            # Keep total_volume_label visible to show final amount
             self.flow_rate_timer.stop()
     
     def send_tube_command(self, index):
         # Only send command if not updating from Arduino response
         if not self.updating_tube_combo:
-            # Send command in format <120> to <145> for tube indices 0-25
-            command_number = 120 + index  # 120-145 for tubes 0-25
-            self.send_command(f"<{command_number}>")
+            # Send command in format <17{tubid}> for tube selection
+            self.send_command(f"<17{index}>")
             self.status_bar.showMessage(f"Schlauchgröße {self.tube_combo.itemText(index)} ausgewählt")
     
     def send_calibration_command(self, ph):
@@ -320,6 +347,8 @@ class PHControllerGUI(QMainWindow):
                         try:
                             flow_rate = float(data[1:])
                             self.flow_rate_label.setText(f"ml/sec: {flow_rate:.4f}")
+                            # Update total volume
+                            self.update_total_volume(flow_rate)
                         except ValueError:
                             pass
         except Exception as e:
diff --git a/ph_controller/ph_controller.ino b/ph_controller/ph_controller.ino
index 0aff296..f8f4183 100644
--- a/ph_controller/ph_controller.ino
+++ b/ph_controller/ph_controller.ino
@@ -302,25 +302,7 @@ if ( RxCmd[1] == '1' ){
     }
     
   }
-} else {
-  // Handle other commands like tube selection <120> to <145>
-  if (RxCmd[0] == '<' && RxCmd[1] == '1') {
-    // Parse 3-digit commands starting with 1
-    int cmd = (RxCmd[1] - '0') * 100 + (RxCmd[2] - '0') * 10 + (RxCmd[3] - '0');
-    if (cmd >= 120 && cmd <= 145) {
-      // Tube selection: 120-145 maps to tube indices 0-25
-      int new_tubid = cmd - 120;
-      if (new_tubid >= 0 && new_tubid <= MAXTUB) {
-        tubid = new_tubid;
-        EEPROM.put(ee_tubid, tubid);
-        Serial.print("<T");
-        Serial.print(tubid);
-        Serial.println(">"); // Bestätigung
-      }
-    }
-  }
-}  
-
+}
 
 
 if (CurrentMode == 0){                        // Nomral Display Mode