|Modified Secchi Scale controls the depth and compares the clarity of the disc on the right to a standard shown on the card to the left.|
|Color spectrometry is used to calculate the pH value. The chart on the left is compared to the chemical-filled water sample on the right.|
An alternative to measuring color through spectrometry is to measure electrical conductivity with a galvanometer and electrodes. Doing so requires specific electrodes and calculations, but not added chemicals. A simple device is the total dissolved solids meter (e.g., Dr. Meter TDS conductivity meter). To learn more, read about ion selective electrodes on Wikipedia. One advantage of using electrodes is the elimination of chemicals and color analysis. Another advantage is automation. For instance, an electrode-based probe can be connected to a smartphone to read, geolocate, calculated, store, and transmit automatically. For instance, Sensorex makes a general smartphone interface for its probes and pH interface for iPhone (approximately $300). YSI has an interesting multi-electrode product that is portable [Meter ($1500), assembly ($1700), and sensors ($450-$1000].
|Sensorex iPhone adaptor and probe.|