The VitaLink ESSENTIALS pH test indicator kit uses a solution known as universal indicator to change a small sample of your nutrient solution to a different colour. Compare this colour to the spectrum chart to indicate what pH your solution is reading at.
Although not as accurate as using a pH meter to analyse your nutrient solution, this indication kit is a quick, precise and cost efficient measure giving over 100 readings.

Spectrum reads solution between pH5.6 and pH7.4 at 0.2 increments.