HM Digital COM-100 Waterproof EC/TDS/Temp Combo Meter Promote They are helpful when plants

They are helpful when plants are under stress

reservoir size of 25 gallons is sufficient for almost any set up

You don't see them

plants must host microbial life in their root zone to ensure proper digestion

HM Digital COM-100 Waterproof EC/TDS/Temp Combo Meter Promote They are helpful when plantsIdeal for all water quality testing, water purification applications, wastewater regulation, aquaculture, hydroponics, colloidal silver, labs & scientific testing, pools & spas, ecology testing, boilers & cooling towers, water treatment and more. The COM 100 is a professional level EC TDS meter at an unbeatable price. Measures electrical conductivity (EC), total dissolved solids (TDS), salinity and temperature. UPGRADED: Four scales: S, mS, ppm, ppt