Bluelab Guardian Monitor — pH, EC & TemperatureBluelab Guardian Monitor 3 in 1 pH, EC & Temperature Display The Bluelab Guardian sits permanently on your reservoir wall and shows you the three numbers that actually matter pH, conductivity (EC ppm TDS CF) and temperature in one glance, 24 7. For growers who want to stop pulling probes in and out of their solution and start monitoring continuously. Why growers choose the Guardian Monitor: Three critical parameters at a glance no pulling pens out of