The detention period in coagulation tanks is usually kept as_______________?
A. 1 to 2 minutes
B. 30 to 45 minutes
C. 2 to 6 hours
D. 2 to 6 days
A. 1 to 2 minutes
B. 30 to 45 minutes
C. 2 to 6 hours
D. 2 to 6 days