Ideal for soilless-grown crops In advanced greenhouses where soilless growth media and hydroponics are employed, the pH of the nutritional solution must be carefully balanced. Haifa Cal™ prime is virtually free of ammonium, thus ideal for soilless crops.   Best for zones of high sun irradiation Accelerated uptake of ammonium by the plant due to intense sun irradiation may result in toxic effects.  Haifa Cal™ Prime assures safe supply of essential calcium with no harmful side-effects.