I was thinking along these lines for the ds182b0:
if (TANK_TEMP < setPointoffHeat)
{
digitalWrite(nutrientheaterRelay,HIGH);} else if (TANK_TEMP < setPointoffHeat +3) {
digitalWrite(nutrientheaterRelay,HIGH,);
If the tank temperature is less than the set point, isn't it also going to be less than the set point + 3?
If the heater is to be turned on when the temperature is less than the set point + 3, why is there a test for/(and same)action for when the temperature is less than the set point?
im unsure what unit to put in where TANK_TEMP is in the if statement so the arduino turns the relay on and off based on the output
First, that isn't what the code does. Second, all capital letter names are reserved (by convention, not by law) for constants. Since TANK_TEMP is, clearly, not a constant, the name shouldn't be all capital letters. The value in the (renamed) variable should be what the sensor returns, in degrees F or C (whichever unit your set point is in).