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I am researching the lifespan of Arduino sensors underwater. I want to measure the water quality of a lake using an Arduino. I have seen that turbidity, temperature, ph and conductivity sensors don´t last long underwater but I can´t find any research on google scholar about the possibles sensors for a 24/7 sensor underwater.

There are some sensors probes available that are robust and they can last up to 3.5 years underwater but the cost is very high. I want to know if there are sensors that can be underwater for long periods of time.

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  • \$\begingroup\$ Does it need to be underwater constantly? My first thought would be to use a small solenoid or motor to periodically dip it into the water, take readings, and then remove it from the water. Or bring a sample cup to the sensor, either way. \$\endgroup\$
    – Hearth
    Jan 18, 2021 at 1:59
  • \$\begingroup\$ Thank you for the fast reply, im actually doing my thesis, i want to propose a real time water quality monitoring based on IoT technology, i have read countless papers about the same topic but they don´t mention the lifetime of these sensors, the common sensors for arduino are for laboratory use and not industrial. Those sensors required maintance and cleaning after using but can´t really find anything on the internet. I will recommend some external sistem in case i don´t find anything else about the sensors that are available- \$\endgroup\$
    – Gerardo Contrera
    Jan 18, 2021 at 2:18
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    \$\begingroup\$ i don't think that there is such a thing as an Arduino sensor \$\endgroup\$
    – jsotola
    Jan 18, 2021 at 2:51
  • \$\begingroup\$ if you want it to last, set it up so that the sensor never directly touches the lake water. If it's not possible, then there will be biological "fouling" ... 3.5 years might be hard. Many water monitoring devices have to get fished out and cleaned every couple years. \$\endgroup\$
    – Pete W
    Jan 18, 2021 at 3:06
  • \$\begingroup\$ Welcome to EE.SE. Please note that asking for components to buy or source in some way is considered as so called "shopping question". This is off-topic on EE.SE. Shopping questions are of limited value on an engineering site like this, because they tend to address only a minimal percentage of the readers and date out very rapidly. \$\endgroup\$
    – Ariser
    Jan 18, 2021 at 13:54

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Temperature, turbidity and conductivity probes that can be continuously submerged are not very expensive, but pH is different. pH probes are made of glass electrodes that exchange ions with the surrounding media. Usually the probes are only briefly exposed to the media to avoid fouling and minimize how gain/loss of ions through the glass. Even then, you'll typically need to recalibrate the probe over time as it gains/loses ions.

Do you really need continuous pH monitoring over such a long time? Can you periodically replace or recalibrate the probe? If not, there are vendors that can do that, but expect the probes to be much more costly than those that are only expected to be briefly exposed to the environment and to only hold a calibration for a short time.

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  • \$\begingroup\$ Thanks for the fast reply, i have read that turbidity sensors like LGZD Sensor V1.1, gives a lot of trouble underwater and can stop working after only 2 weeks. For the pH sensors i will recommend using the SKU-SEN0169 industrial sensor that last up to one year underwater and it only cost $60 but is the only industrial sensors that i could find, the temperature, turbidity and conductivity sensors are only for short periods of time underwater. I found it weird that a lot of research papers of the same topic don´t mention these kind of trouble. \$\endgroup\$
    – Gerardo Contrera
    Jan 18, 2021 at 2:26

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