Internet of Things (IoT)

Water Quality, for pools and ponds

29 October 2019

We bought 9 Comet (a type of goldfish) and put them in a water plant filled oasis, at least that is what we thought until 6 of them didn’t survive three weeks.

To make matters worse the three remaining fish developed a disease called Ich.

A bit of research and I knew that I need to not only have plants to remove nasties from the water but that I also need to keep the dissolved oxygen high (using a pump and a bit of a waterfall), pH within a tight band and watch the temperature of the water to prevent these events from recurring again.

I built a lovely little Wifi-enabled pH and Temperature sensor and was sending the data to a website.

I then decided that it needs a battery pack and so modified it to accept such a pack and charging from a standard USB lead. I now also use it to check my pool water. I also added oxidation and reduction potential, also called “ORP” as a bit of research tells me this is a good indication of water quality!


The waterproof temperature sensor. I use it to monitor pond, pool and my home office temperatures.
The ESP32 integrated micro-processor and Wifi are inside an old underwater camera case. The three key values are shown on the display.
A BNC-type connector serves to connect both the blue pH and the black ORP sensors which are stored in their buffer solution caps strapped to the box (the internal battery is charged using the USB socket shown)
A simple button is used to switch the ESP32 ON and OFF to attain a full charge of the battery.

I am a huge fan of Thingspeak and the MQTT API for sending data to their cloud IoT ecosystem. For those so inclined, it allows for some rich data analysis and visualisations as Mathworks are the holding company thereof. Mathworks of MATLAB simulation game.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.