Hi, I have been working with the hydroponics project where I am trying to measure the temperature, humidity and pressure parameters by using BME680 sensor but to test the PH parameters.
I am looking for the sensor which will help me to test the pH scale of water solvents as I have searched about Soil and moisture sensor but I still sought to confused with this kind of sensor.

The suggestion about how to use this sensor or the alternative sensor to measure the PH scale will be a great help.

 

Hi, I have been working with the hydroponics project where I am trying to measure the temperature, humidity and pressure parameters by using BME680 sensor but to test the PH parameters.
I am looking for the sensor which will help me to test the pH scale of water solvents as I have searched about Soil and moisture sensor but I still sought to confused with this kind of sensor.

The suggestion about how to use this sensor or the alternative sensor to measure the PH scale will be a great help.

How will you be interfacing to the sensor? What level of accuracy and precision do you require?

 

Hi, I will be interfacing the sensor with Raspberry Pi using I2C communication,
Actually being new to this kind of work I don't have that much knowledge but for the test, accuracy must be around 1% of detecting range and precision must be around +/- 0.5

 

Hi, I will be interfacing the sensor with Raspberry Pi using I2C communication,
Actually being new to this kind of work I don't have that much knowledge but for the test, accuracy must be around 1% of detecting range and precision must be around +/- 0.5

Well, there’s this: https://www.sparkfun.com/products/10972

 

I am looking for the sensor which will help me to test the pH scale of water solvents as I have searched about Soil and moisture sensor but I still sought to confused with this kind of sensor. The suggestion about how to use this sensor or the alternative sensor to measure the PH scale will be a great help.

Are you trying to measure the pH of a solution in water or the pH of soil? The sensor you link to is for soil moisture, yet you talk about hydroponics.

The SparkFun sensor is only for solutions. While you may get a number from soil, it may not be very accurate.

 

Well this one is much costlier, is there anything else which will help me out or any specific analog sensor to work with this kind of stuff?

 

Well this one is much costlier, is there anything else which will help me out or any specific analog sensor to work with this kind of stuff?

What "kind of stuff" are you trying to measure the pH of?

 

I'm a retired Process Control Engineer from a Chemical Refinery and I can tell you measuring Ph is extremely problematic. It is truly a "Black Art". The glass sensor tubes are delicate and need a lot of close attention, constant recalibration, and frequent replacement (not cheap). I took a Foxboro Instruments course taught by a senior gentleman who was the Instrument Engineer responsible for the research and development of Ph measurement instruments. Measuring liquid Ph is one thing, but actual soil Ph... Hmm... The only way we could verify that the Ph instrument was working properly was by comparing it's reading against lab analysis of samples taken every shift (8 hours). There was a regular schedule for sensor calibration which was fairly often (don't remember). If it couldn't be calibrated it had to be replaced which was several times a month.

 

Measuring liquid Ph is one thing, but actual soil Ph... Hmm...

A lot of people think pH is a number on a meter. It is the negative logarithm of the hydrogen ion concentration (activity). With a liquid like a hydrocarbon, you can still define the pH. It is very high (well above "14") and cannot be measured with a typical meter. That doesn't mean that sticking a pH electrode in benzene or other non-aqueous solution won't give a number. I have seen a professor of chemistry at a small college make that mistake with the bio-diesel he was making from used cafeteria cooking oil. He was worried about excess alkali or acid ruining his Mercedes. I suggested mixing his diesel with water and measuring the pH of the water. As an added caution, high-purity distilled water will give erroneous pH readings too. You have to add a tiny amount of "neutral" salt. KCl is often used for that.

Thus, when someones says they want to measure the pH of "stuff," I try to get a better understanding of what that stuff is. Soil per se would be impossible to measure with any meter I know of. If one is talking about a mixture of soil with water, measuring the pH of the water is simple. Measuring the pH of other liquids needs a lot more considerations.

 

Long ago pH meters used expensive mV meters and expensive probes.
A digital millivolt meters can also be purchased inexpensively. This leaves the need of a probe
and conversion to correct units

The Vantakool probe completes the mission, it does most everything if care is taken in the use and calibration.

Building your own takes on a more open pathway for modification to hydroponics.
However what hydroponic people are saying is valuable in accomplishing the end result.

 

Quick peek at Wiki "Precise, repeatable measures of soil pH are required for scientific research and monitoring. This generally entails laboratory analysis using a standard protocol; an example of such a protocol is that in the USDA Soil Survey Field and Laboratory Methods Manual.[6] In this document the three-page protocol for soil pH measurement includes the following sections: Application; Summary of Method; Interferences; Safety; Equipment; Reagents; and Procedure."

Yes, they sell soil Ph meters at Walmart and gardening stores. How accurate they are (or not at all) is questionable to me. A typical industrial process meter is thousands of dollars and it's accuracy is dependant on many factors such as correct application, correct installation, calibration, testing, maintenance, etc. Then there may be regulatory compliance issues depending on the application (don;t get me started on due diligence). Start with the end result and work backward. What are you measuring, is there a standard for that, what is the methodology, is there an instrument to do that, what are it's specifications, how do I design a system to communicate with the instrument that meets that specification, how do I display that, do I need to alarm, is a fail-safe state needed, etc. Good luck and let us know how it goes.