... Typical measured values Fe, % , ≥18.519.1Reducing substances (counted by Fe2+), % , ≤0.150.01Basicity, %9.0-14.014. ... of SPFS for the raw water to be treated by sample test prior to use. 1. Preparation ... according to the formation and settling of flocs by sample test. For treatment of tap water under ... good capture effect and filtration speed. This is a key step for improvement of water quality. 7. SPFS ...