Price: $499.95 CAD
The Guardian, by Blue Lab, i the simplest and most effective reservoir monitor you could ever own!
It offers full continuous coverage of pH, conductivity (EC/TDS/CF), and temperature within a nutrient solution.
It's designed for indoor use, and can be easily mounted on the wall or hung from a bar.
Simply set high and low alarm states – if the solution moves away from the ideal range, the display flashes. A quick look at the monitor will let you know when your nutrient solution needs adjusting.
more info at Blue Lab