A.0.0l~0.03mg/L B.0.1~0.3mg/L C.0.1~0.3ug/L D.0.3~0.5mg/L
A.2~8°dH B.10~16°dH C.1~2°dH D.16~20°dH
A.5~8°dH B.8~12°dH C.-5~0°dH D.0~5°dH