General Hydroponics® Hardwater FloraMicro, 6 Gallon

General Hydroponics® Hardwater FloraMicro, 6 Gallon: Excessive Calcium is the main factor in your decision to use FloraMicro Hardwater. If the total dissolved salts (TDS) in your water supply measure 200 ppm or more, we recommend that you obtain a water analysis to determine Calcium content. If the analysis reveals a Calcium content of more than 70 ppm (mg/liter) then you should use FloraMicro Hardwater instead of regular FloraMicro.