diff --git a/Arduino/CanGrow/CanGrow.ino b/Arduino/CanGrow/CanGrow.ino
index 4f969e6..0597d8f 100644
--- a/Arduino/CanGrow/CanGrow.ino
+++ b/Arduino/CanGrow/CanGrow.ino
@@ -38,6 +38,11 @@
 // DHT support dropped
 // https://github.com/adafruit/DHT-sensor-library
 // #include "DHT.h"
+// SHT30/31 
+// https://github.com/adafruit/Adafruit_SHT31/
+#include "Adafruit_SHT31.h"
+
+
 
 /*
  * CanGrow header files
@@ -80,9 +85,6 @@ void setup() {
   // set FAN2 to off with digitalWrite LOW
   analogWrite(PinFAN2, PinFAN2PWM);
   
-  // set PWM frequency to 13.37KHz
-  analogWriteFreq(13370);
-
   // Start EEPROM
   EEPROM.begin(512);
 
@@ -132,6 +134,22 @@ void setup() {
     Serial.println("!! Cannot find BME280 on I2C bus. Please check connection or ID");
   }
   
+  // initialise SHT31
+  Serial.println(":: initialise SHT31 sensor ::");
+  if (! sht31.begin(0x44)) {   // Set to 0x45 for alternate i2c addr
+    Serial.println("Couldn't find SHT31");
+  }
+  
+  Serial.print("SHT31 Heater Enabled State: ");
+  if (sht31.isHeaterEnabled())
+    Serial.println("ENABLED");
+  else
+    Serial.println("DISABLED");
+  
+  
+  
+  
+  
   Serial.println("To wipe the EEPROM saved data, set D4 (PinWIPE) to LOW - NOW! (2 seconds left)");
   // wait a few seconds to let the user pull D4 down to wipe EEPROM
   // and we can enjoy the boot screen meanwhile :p
@@ -198,12 +216,16 @@ void setup() {
     display.display();
   }
 
-  // at the end of setup, set the outputs
+  // at the end of setup, set the outputs, when configured true
   // we do this here because otherwise on inverted
   // boards like CanGrow PCB v0.6 it would be turned on
-  pinMode(PinLED, OUTPUT);
-  pinMode(PinPUMP, OUTPUT);
-  pinMode(PinFAN, OUTPUT);
+  if(configured == true) {
+    pinMode(PinLED, OUTPUT);
+    pinMode(PinPUMP, OUTPUT);
+    pinMode(PinFAN, OUTPUT);
+    // set PWM frequency
+    analogWriteFreq(PWMFrequency);
+  }
 }
 
 
diff --git a/Arduino/CanGrow/CanGrow_Init.h b/Arduino/CanGrow/CanGrow_Init.h
index 4632880..41a377a 100644
--- a/Arduino/CanGrow/CanGrow_Init.h
+++ b/Arduino/CanGrow/CanGrow_Init.h
@@ -105,6 +105,8 @@ bool UseLEDrelais;
 bool UseFANrelais;
 // Which temperature sensor to use?
 byte TemperatureSensor_Type;
+// which humidity sensor to use
+byte HumiditySensor_Type;
 unsigned short MaintenanceDuration = 300;
 char Esp32CamIP[16];
 // PumpLastOn (long) timestamp
@@ -112,6 +114,7 @@ unsigned long PumpLastOn;
 bool OutputInvert;
 unsigned short SoilmoistureWet;
 unsigned short SoilmoistureDry;
+unsigned short PWMFrequency = 13370;
 
 
 
@@ -141,9 +144,9 @@ byte SunriseHour = 7;
 byte SunriseMinute = 0;
 // PinLEDPWM - contains the PWM value for dimming the grow light
 // default is 255 to ensure it is just on for the case UseLEDrelais is true
-byte PinLEDPWM = 0;
-byte PinFANPWM = 0;
-byte PinFAN2PWM = 0;
+byte PinLEDPWM = 255;
+byte PinFANPWM = 255;
+byte PinFAN2PWM = 255;
 
 // fade in and out sunrise and sunset?
 bool SunFade;
diff --git a/Arduino/CanGrow/CanGrow_Sensors.h b/Arduino/CanGrow/CanGrow_Sensors.h
index c41f101..05d3034 100644
--- a/Arduino/CanGrow/CanGrow_Sensors.h
+++ b/Arduino/CanGrow/CanGrow_Sensors.h
@@ -14,7 +14,15 @@
 #define SEALEVELPRESSURE_HPA (1013.25)
 Adafruit_BME280 bme;
 
-
+/*
+ * SHT30/31 Stuff
+ * 
+ */
+ 
+ bool enableHeater = false;
+ Adafruit_SHT31 sht31 = Adafruit_SHT31();
+ 
+ 
 /*
  * Chirp functions
  */
@@ -97,6 +105,7 @@ float getTemperature(byte tempSensor) {
    * ==========
    * 1 : DHT11 temp sensor
    * 2 : chirp I2C temp sensor
+   * 3 : SHT31
    */
 
   float temperature = 0;
@@ -113,6 +122,10 @@ float getTemperature(byte tempSensor) {
       // read temperature from chrip I2C
       temperature = readI2CRegister16bit(0x20, 5) * 0.10 ;
       break;
+    case 3:
+      // read temp from SHT31
+      temperature = sht31.readTemperature();
+      break;
     default:
       // if sensor type is not recognized, return 99
       temperature = 99.99;
@@ -121,10 +134,30 @@ float getTemperature(byte tempSensor) {
    return temperature;
 }
 
-float getHumidity() {
-  // dht support dropped
+float getHumidity(byte HumSensor) {
+  
+  /*
+   * sensors:
+   * 1: BME280
+   * 2: SHT31
+   * 
+   */
+  float humidity;
+  
+  switch(HumSensor) {
+    case 1:
+      humidity = bme.readHumidity();
+      break;
+    case 2:
+      humidity = sht31.readHumidity();
+      break;
+    default:
+      humidity = 0.0;
+      break;
+  }
+  
   // return dht.readHumidity();
-  return bme.readHumidity();
+  return humidity;
 }
 
 int getSoilmoisture(byte moistureSensor, bool returnRAW = false) {
diff --git a/Arduino/CanGrow/CanGrow_SysFunctions.h b/Arduino/CanGrow/CanGrow_SysFunctions.h
index 9af08f6..f2531c9 100644
--- a/Arduino/CanGrow/CanGrow_SysFunctions.h
+++ b/Arduino/CanGrow/CanGrow_SysFunctions.h
@@ -111,7 +111,9 @@ bool loadEEPROM() {
    * 244 SoilmoistureWet (2 byte)
    * 246 SoilmoistureDry (2 byte)
    * 248 PinFAN2PWM (1 byte)
-   * 249 ...
+   * 249 HumiditySensor_Type (1 byte)
+   * 250 PWMFrequency (2 byte)
+   * 252 ...
    * 
    */
    
@@ -183,6 +185,8 @@ bool loadEEPROM() {
       EEPROM.get(244, SoilmoistureWet);
       // size is 1 byte
       EEPROM.get(246, SoilmoistureDry);
+      // size is 1 byte
+      EEPROM.get(249, HumiditySensor_Type);
     }
     // TODO auth does not work atm 
     // EEPROM.get(160, WebUiUsername);
@@ -223,6 +227,8 @@ bool loadEEPROM() {
       EEPROM.get(242, PumpIntervalBloom);
       // size is 1 byte
       EEPROM.get(248, PinFAN2PWM);
+      // size is 2 byte
+      EEPROM.get(250, PWMFrequency);
       
     }
 
@@ -269,6 +275,11 @@ bool loadEEPROM() {
     Serial.println(SoilmoistureWet);
     Serial.print("SoilmoistureDry: ");
     Serial.println(SoilmoistureDry);
+    Serial.print("HumiditySensor_Type: ");
+    Serial.println(HumiditySensor_Type);
+    Serial.print("PWMFrequency: ");
+    Serial.println(PWMFrequency);
+
 
     Serial.println("---- Grow values ----");
     Serial.print("GrowName: ");
@@ -547,7 +558,7 @@ void refreshSensors() {
   byte soilmoistureAvgSampleCount = 5;
   
   valSoilmoisture = getSoilmoisture(MoistureSensor_Type);
-  valHumidity = getHumidity();
+  valHumidity = getHumidity(HumiditySensor_Type);
   valTemperature = getTemperature(TemperatureSensor_Type);
   valWaterlevel = getWaterlevel();
   
diff --git a/Arduino/CanGrow/CanGrow_Version.h b/Arduino/CanGrow/CanGrow_Version.h
index b152786..07ba194 100644
--- a/Arduino/CanGrow/CanGrow_Version.h
+++ b/Arduino/CanGrow/CanGrow_Version.h
@@ -1,5 +1,5 @@
 /* CanGrow_Version.h gets generated from cangrow.sh */
 
 const char* CanGrowVer = "0.1-dev";
-const char* CanGrowBuild = "61c7af5-20241208140924";
+const char* CanGrowBuild = "5df2d0f-20241208233808";
 
diff --git a/Arduino/CanGrow/CanGrow_WebFunctions.h b/Arduino/CanGrow/CanGrow_WebFunctions.h
index 07e2c4a..8ec05bd 100644
--- a/Arduino/CanGrow/CanGrow_WebFunctions.h
+++ b/Arduino/CanGrow/CanGrow_WebFunctions.h
@@ -640,7 +640,7 @@ void WEBsystemSettings() {
     // SoilmoistureLow byte
     body += "Soilmoisture low: <input class='inputShort' type='number' name='SoilmoistureLow' min='0' value='";
     body += SoilmoistureLow;
-    body += "' required> %<br>\n";    
+    body += "' required> %<br>\n";
     
     // SoilmoistureWet byte
     body += "Soilmoisture wet: <input type='number' id='iSoilmoistureWet' name='SoilmoistureWet' min='0' value='";
@@ -668,6 +668,16 @@ void WEBsystemSettings() {
       }
     body += "<option value='1'" + returnStrSelected(TemperatureSensor_Type, 1) + ">I2C BME280</option>\n";
     body += "<option value='2'" + returnStrSelected(TemperatureSensor_Type, 2) + ">I2C Chirp</option>\n";
+    body += "<option value='2'" + returnStrSelected(TemperatureSensor_Type, 3) + ">I2C SHT31</option>\n";
+    body += "</select><br>\n";
+    
+    // HumiditySensor_Type byte
+    body += "Humidity sensor: <select id='HumiditySensor_Type' name='HumiditySensor_Type' required>\n";
+    if(configured == false) {
+      body += "<option disabled value='' selected hidden>---</option>\n";
+      }
+    body += "<option value='1'" + returnStrSelected(HumiditySensor_Type, 1) + ">I2C BME280</option>\n";
+    body += "<option value='2'" + returnStrSelected(HumiditySensor_Type, 2) + ">I2C SHT31</option>\n";
     body += "</select><br>\n";
     
     // NtpOffset int
@@ -679,6 +689,10 @@ void WEBsystemSettings() {
     body += MaintenanceDuration;
     body += "' required> Seconds<br>\n";
     
+    // PWMFrequency short
+    body += "PWM Frequency: <input type='number' name='PWMFrequency' min='0' max='20000' value='";
+    body += PWMFrequency;
+    body += "' required> Hz<br>\n";
     
     body += "ESP32-Cam IP (optional): <input type='text' name='Esp32CamIP' maxlength='16' value='";
     body += Esp32CamIP;
@@ -864,6 +878,8 @@ void POSTsystemSettings() {
   
   unsigned short UseLEDrelais_old = UseLEDrelais;
   unsigned short UseFANrelais_old = UseFANrelais;
+  unsigned short PWMFrequency_old = PWMFrequency;
+  
   NtpOffset = webserver.arg("NtpOffset").toInt();
   MoistureSensor_Type = webserver.arg("MoistureSensor_Type").toInt();
   SoilmoistureLow = webserver.arg("SoilmoistureLow").toInt();
@@ -879,8 +895,16 @@ void POSTsystemSettings() {
   OutputInvert = webserver.arg("OutputInvert").toInt();
   SoilmoistureWet = webserver.arg("SoilmoistureWet").toInt();
   SoilmoistureDry = webserver.arg("SoilmoistureDry").toInt();
+  HumiditySensor_Type = webserver.arg("HumiditySensor_Type").toInt();
+  PWMFrequency = webserver.arg("PWMFrequency").toInt();
   
-  configured = true;
+  // when configured is false, set it to true and ensure outputs are set
+  if(configured == false) {
+    configured = true;
+    pinMode(PinLED, OUTPUT);
+    pinMode(PinPUMP, OUTPUT);
+    pinMode(PinFAN, OUTPUT);
+  }
   
   // size is 1 byte
   EEPROM.put(161, configured);
@@ -907,6 +931,8 @@ void POSTsystemSettings() {
   EEPROM.put(243, OutputInvert);
   EEPROM.put(244, SoilmoistureWet);
   EEPROM.put(246, SoilmoistureDry);
+  EEPROM.put(249, HumiditySensor_Type);
+  EEPROM.put(250, PWMFrequency);
   
   // write data to EEPROM
   EEPROM.commit();
@@ -935,6 +961,11 @@ void POSTsystemSettings() {
     Serial.println("UseFANrelais is 0, forcing PinFANPWM to max to prevent relais damage and ensure its turned on");
   }
     
+  if(PWMFrequency != PWMFrequency_old) {
+    // if PWM freq changed, apply new settings
+    analogWriteFreq(PWMFrequency);
+  }
+  
   Serial.print("configured: ");
   Serial.println(configured);
   Serial.print("UseFan: ");
@@ -1171,7 +1202,7 @@ void APIgetDebug() {
   
   // BME280
   objSensors["bme280"]["temperature"] = getTemperature(1);
-  objSensors["bme280"]["humidity"] = getHumidity();
+  objSensors["bme280"]["humidity"] = getHumidity(1);
   objSensors["bme280"]["preassure"] = bme.readPressure() / 100.0F;
   objSensors["bme280"]["appAltitude"] = bme.readAltitude(SEALEVELPRESSURE_HPA);
   
diff --git a/cangrow.sh b/cangrow.sh
index 59c9315..d7b5c20 100755
--- a/cangrow.sh
+++ b/cangrow.sh
@@ -33,7 +33,7 @@ test -z $1 && help
 case $1 in
 	s|setup)
 		ACLI_DIR="$(dirname $ACLI)"
-		declare -a LIBS=( "Adafruit SSD1306" "Adafruit BME280 Library" "ArduinoJson" "NTPClient" "Time" )
+		declare -a LIBS=( "Adafruit SSD1306" "Adafruit BME280 Library" "ArduinoJson" "NTPClient" "Time" "Adafruit SHT31 Library" )
 		echo ":: Setting up build environment for CanGrow Firmware."
 		echo "   This will download the binary for arduino-cli and install"
 		echo "   the packages for the arduino ide from the debian repository."