Go Down

Topic: PAID simple Aquarium regulator with Peltier Cooler (Read 539 times) previous topic - next topic


Hello! I am attempting to make a heating/cooling device for my aquarium. it is on my porch, so cooling is essential in the florida heat. I would like to do the following:

Use a DS18B20 Digital (waterproof) Temperature sensor (2x) to control the activation (and heat/cool switching) of a 60W peltier unit. I am attempting to use an arduino nano (chinese knockoff) and my only two inputs are the temp sensors.


temp1 (DS18B20), pin D2
temp2 (DS18B20), pin D4


PolarityRelay (All *Relay* are 5v, so just HIGH or LOW to control), D7

PwrRelay, D8

PumpRelay, D12

HeatLED, D3

CoolLED, D5

WaitLED, D6

ErrorLED, D9


* Take Average of 2 temp sensors.

*As long as two sensors are within 3 degrees(F) of eachother:           /*This is a condition on the
                                                                                                     bottom, but how I figure it would
                                                                                                     be inserted into the code*/

      If temp is >78F {
                     relay (Pump) ON;
                     CoolLED ON;
                     PWR Relay ON;
----------monitor temp, until temp reaches 77.0 degrees (average), then:     //+ or -, i dont want to
                                                                                                           // ask too much of the sensor

                    pwr relay OFF;

                    Cool LED OFF;

                    after one minute, pump relay OFF;

           If temp < 76.3 deg:
                polarityRelay ON;
                Pump Relay on;
                heat LED ON;

                Pwr Relay ON;

------- monitor until 77.3F Average, THEN

                Pwr relay off;
                polarity relay off;
                heat LED off;

                after 1 minute, turn off pump relay


If two temp sensors are >3 degrees apart, dont heat or cool, dont turn on the pump, just turn on the error LED. open to other suggestions for what to do, but this is my failsafe for a temp sensor failing.

Must wait 10 minutes + recheck temp before switching from hot/cold functions. I don't want it switching back and forth all the time.


I would LIKE to be able to understand what variables are where, so I can tweak it once I have it hooked up to my aquarium when I finish assembly of the this thing.

I can mail you cash, use paypal, or pay in toilet paper (single ply only, sorry).

message me here, or at agrady1995@gmail.com.

I work m-s 7am to 3pm so I wont be able to reply immediately, most likely.


Hi agrady, just curious - how are you heat/cold sinking the unused side of the petltier?

There are 10 types of people in the world, those who understand binary, and those that don't.


Hi agrady, just curious - how are you heat/cold sinking the unused side of the petltier?

Haha! Scrolled down to ask the same question.

I actually have a liquid to liquid petltier heat exchanger. Fun little toy to play with.

-jim lee
PNW Ardiuno & Maker club
1012 9Th Street, Anacortes, WA 98221 (Around the back of building)

Go Up