Pool Sensor (analog)

  • I want to measure the temperature of my pool. I already have a Sensor in my Pool Equipment from the Solar Controller and I want to use this.
    Unfortunately this Sensor has only two wires and it's only a Resistor I guess.
    Is it possible to use this Sensor for Temperature monitoring?

  • Mod

    @netbus Judging from the resistance to temperature conversion table in its controller manual (1Kohm at 0 degrees, chapter B.2) I would expect the sensor is in fact a PT1000 thermocouple.
    The web is full of examples how to use a thermocouple on an arduino.

  • Hero Member

    @netbus I use the waterproof version of DS18B20 in my pool sensor and it works perfectly, 3 years now and counting 😉

  • I was initially going to try something similar with my pool as I have a existing Solar heating system that has sensors in the Pool pump and solar return pipework. After a bit of experimentation I discovered it used 33k NTC themistors to do the sensing.

    Rather than add additional parts I ended up putting 2 DS18B20s, one directly in the pool and one in the return solar pipe using a drill bit and some epoxy. I put the main board in a box with a solar panel on top and a 18650 battery and charger circuit. It works really well.

    My concern was tapping into the current sensors may load down or damage the solar controller which is no longer manufactured and would be hard to repair.
    If you can workout the resistance of you sensors at differing temperatures you can work out the resistance and K factor of the sensors. There are some online calculators that let you work it out based on taking 3 readings at differing values. I cheated and used a pot in place of the existing sensor to give me variable resistance and then read the level from the controller. This allowed me to map resistance to the sensed temprature. I used this website with a low / medium and high resistance reading https://www.thinksrs.com/downloads/programs/therm calc/ntccalibrator/ntccalculator.html


  • @Yveaux
    Yes, it's a pt1000 sensor.
    Is it possible to use the existing sensor on my solarcontroller and in parallel with an arduino or do I need an additional sensor?

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