pH meter to monitor aquariums & hydroponics using Raspberry Pi, Arduino, ESP8266

Description

The HomeLab-pH is a circuit board intended for pH measurements.
The measured values are corrected for temperature changes by an included waterproof thermometer.
Here the board is sold in a set with the HomeLab-Isol digital isolator module. Using both in tandem gives stable and unbiased on-line pH measurements for aquaristics and hydroponics. More generally this set is applicable for all cases where pH-measurements are affected by electrical appliances immersed in the measured liquid. Another example is the progress monitoring of fermentation in beverage and wine production.
There are many cases where adding a digital isolator module does not benefit the measurements accuracy. For instance when samples are measured in a beaker, or measurements are made directly in a pool, or in volumes with no working electrical appliances, or when the HomeLab-pH module is battery operated. In these cases measuring with HomeLab-pH alone will suffice and give unaltered pH-values. To purchase HomeLab-pH module alone please visit:
https://www.ebay.com/itm/142423993924
If instead
only
the isolater module is needed visit:
https://www.ebay.com/itm/
142982309889
The HomeLab-pH module is just a measuring block. It has to be assisted by an external CPU-board and corresponding software to perform the calculations. Software packages for Raspberry Pi computer, Arduino controller and ESP8266 modules are freely available to download from the HomeLab-pH companion site at homelab.link. They give the user interface to log and visualize the measured values, as well as to calibrate the board.
When connected to Arduino or ESP8266 the module can be controlled by the user visually at the console. Alternatively both can act as a data server for HomeLab-pH, which can be accessed by a remote machine through a special communication protocol. The user may program additional functionality using the available HomeLab_pH library for Arduino IDE.
As an expansion board to Raspberry Pi viewing the readings or calibrating is as simple as pointing a smart-phone browser to the Pi's LAN address. The module can also be accessed at the RPi console or even with requests over http.
Features
Board
Accurate and stable voltage reading ensures a resolution of 0.01 pH over the 0 – 14 pH range.
Wide input voltage range suitable also for ORP measurements.
A digital temperature sensor to compensate pH for temperature impact (ATC).
Socket with Raspberry Pi compliant pinout.
A LED and a button for user interaction.
Supported by free software for Raspberry Pi, Arduino or ESP8266.
Each board is tuned and tested.
Software options for Arduino, ESP8266
A library for Arduino IDE.
Simple visual interface to read and calibrate the module.
Remote access by means of a special protocol (read and calibrate).
Software for Raspberry Pi
Rich visual interface for module calibration and data viewing, logging and management.
Periodic unassisted measurements.
Access to the measured data remotely via an http call or locally at the OS console.
Visual interface for Raspberry Pi
Simultaneous visualization of pH, temperature and voltage values.
Accessible from every device with an installed browser.
Manage, list and plot data from periodic unassisted measurements or points at user choice.
Calibration with many options - temperature compensated data for 13 buffer solutions and an option to use the sensor’s isopotential data.
pH range: 0 ÷ 14 pH
pH resolution: 0.01 pH
Board specification
input voltage range:
-900 mV ÷ 2048 mV
supply voltage:
3.3 to 5 V
resolution
pH 3 - pH 11:
0.002 pH
pH inaccuracy*:
(temperature adjusted)
pH 4 to 10:
not more than 0.03 pH
pH 2 to 12:
not more than 0.05 pH
overall dimensions, W:H:D:
59 : 37 : 36 mm (2.3 : 1.5 : 1.4 in)
board dimensions, W:D:
56 : 20 mm (2.20 : 0.79 in)
* The inaccuracy of the measurement depends on the precision of the performed calibration. The specified value is valid for 2-point calibration where the buffers' inaccuracy is not greater than 0.02 pH units and their temperature difference with the sample is less than 5°C. If calibration buffers of  ± 0.01 pH are used, the inaccuracy of the measured pH value may be even lower.
Temperature sensor
response time at 90%:
typical less than 10 s, max 20 s (stirred water)
inaccuracy:
not more than 0.5°C ( 0.9°F )
working range:
-10 ÷ 85°C (14 ÷ 185°F)
tip diameter:
ø 6 mm
cable length:
about 1 m ( 3'3" ); easily extendable by PS/2 M/F extension cable
What is in the box?
(shown at one of the pictures above)
A HomeLab-pH circuit board
A
HomeLab
isolator circuit board
A digital temperature sensor
A mounting set of:
4 screws (M2.5) and a nut
3 spacers – 2x12 mm and 1x25 mm.
A leaflet containing mounting and usage instructions
Attention
: a combination pH-probe is not included.