Budget pH & Conductivity Duo – A Low-Cost Teaching Kit Using Off-the-Shelf Probes and Arduino
Affordable titrations and water-quality testing for real classrooms
Traditional pH meters and conductivity meters are accurate — but expensive, fragile, and often supplied as standalone units that schools struggle to replace. When you’re trying to equip a science lab, run demonstrations, or teach online from a studio, buying multiple commercial units simply isn’t practical.
At Philip M Russell Ltd, we’ve been developing a budget pH + conductivity combo kit using off-the-shelf probes, a simple Arduino, and a set of open-source libraries. The goal is to create a tool that is:
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affordable
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easy to repair
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simple to calibrate
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robust enough for students
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flexible for titrations or water-quality investigations
It turns out you can get excellent results for a fraction of the cost.
Why Build Your Own?
Science teaching benefits enormously from cheap, replaceable, modular equipment.
A DIY solution gives you:
1. Low Cost
Commercial meters often cost £80–£300 each.
Our Arduino-based version costs under £40 including both probes.
2. Easy Repairs
Drop it? Spill acid on it?
Replace just the probe — not the whole unit.
3. Modular Design
The same Arduino board can also:
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log temperature
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run colour sensors
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measure dissolved oxygen
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support environmental monitoring projects
4. Ideal for Student Use
Students can see the electronics, understand the sensor, and even modify the code.
This makes it perfect for GCSE and A Level required practicals, as well as fieldwork.
The Hardware – Simple, Reliable, Replaceable
pH probe
Off-the-shelf BNC pH probes are inexpensive and widely used.
They require:
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a BNC interface board (cheap and stable)
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two-point calibration (pH 4 / pH 7 or pH 7 / pH 10)
Conductivity probe
Basic EC probes connect to a small amplifier module.
These give surprisingly good readings for:
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titrations
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investigating ionic strength
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river-water comparison
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checking tap water hardness
Arduino Uno / Nano
Provides:
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analogue inputs
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USB or wireless connection
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easy integration with laptops or Chromebooks
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simple coding environment
It uploads data directly to the computer — perfect for plotting titration curves.
Example Experiments the Duo Can Handle
1. pH Titration With Real-Time Graphing
The Arduino outputs pH every second as acid is added.
Students see the equivalence point appear live on the curve — extremely satisfying.
2. Conductivity vs Concentration
A simple, reliable experiment for ionic solutions.
Useful for teaching ions, strong/weak acids, and bonding.
3. Water-Quality Comparison
Measure conductivity in:
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tap water
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river water
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distilled
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rainwater
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bottled waters
Great for both Chemistry and Going Green sustainability links.
4. Neutralisation Investigations
Compare:
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strong acid + weak base
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weak acid + strong base
using pH and conductivity simultaneously.
The Software – Open Source, Easily Modified
We use a simple Arduino sketch that:
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reads both sensors
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averages readings to reduce noise
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outputs values over serial
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logs data in CSV
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supports temperature correction for conductivity
Students can see every line of code and adapt it for coursework or projects.
Why This Matters for Teaching
The biggest advantage of a low-cost kit is that students can experiment more often.
Instead of protecting expensive meters, they can:
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take multiple readings
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run repeated tests
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work in groups
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investigate their own questions
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build confidence with data
It’s exactly what practical science should be.
The Takeaway
A budget pH & conductivity duo built around an Arduino is:
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far cheaper than commercial meters
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flexible and repairable
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perfectly accurate for classroom work
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ideal for titrations and environmental studies
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great for cross-curricular sustainability content
Research and development like this helps us offer better teaching resources without relying on expensive proprietary equipment.
Sometimes the best science kit is the kit you build yourself.
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