## Introduction: Arduino Pond Temperature Sensor

Since I have a fish pond in my house that the water temperature can’t be cooler than 15 Celsius, neither the temperature above 30 Celsius in order to let the fish survive. So we will do is the temperature sensor for the pond.

How it works:
The pond temperature sensor that can automatically detect and tells when the temperature is below 15 Celsius it will light the blue light, so you can tell that is too cold for the fish, so you can go and turn on the heater. However, if the temperature is too high, it will automatically light the yellow light to show you that the temperature is too high for the pond, so you can go and turn on the cooler.

## Step 1: Materials

Arduino *1

Arduino Thermistor *1

Wire *9

Film Resistor *1

Resistor *2

LED Red *1

LED Blue *1

Box *1

Transparent Tape

*1 Scissor *1

Utility Knife *1

## Step 2: Cardboard

Leave a side of the box is able to open if the box wasn’t, so you can put your Arduino inside the box, and able to take it out whenever you want.

Use a Utility Knife to cut out a hole on the top of the box, and use the scissors to cut out a piece of transparent tape to cover the hole, so it won’t feel likes is actually a hole there, but the light of the LED can still come out from the box. Use Utility Knife to cut a hole on the left side of the box so you can plug your Arduino inside it.

## Step 3: Circuit

Follow the figure above to finish your circuit nicely.

Note: We are using Arduino Leonardo

The temperature sensor we are actually using is thermistor instead of the temperature sensor on the diagram, so please use the actual picture one.

The resistor above, on the thermistor, is not the film resistor which is the blue resistor we are supposed to using.

## Step 5: Combine

Make the wire that connects the Arduino to Computer cross through the hole we made on the left side of the box, and plug it on the Arduino.

Put the Arduino inside the box, and make the thermistor toward the outside of the box.

## Step 6: Operating

Put the box where next to the pond you get nicely, and be careful to not to let it touch the water, because it’s not waterproof.

Open the side of the box so the thermistor can detect the temperature outside.

If the light shows yellow, open the cooler, because it is too hot for the fish.

If the light shows blue, open the heater, because it is too cold for the fish