DAVIES "POOL-KLEEN" is a concentrate, and should be diluted 5:1 with water.  For more severe stains and scum lines, dilute 2:1 with hot water.  Apply with brush or for large area, mop.  Rinse very well with hot water. DAVIES "POOL-KLEEN" is a mild acid product and should be handled with respect.  Small amount of cleaner entering the pool will not affect pool water chemistry; however, larger amounts may lower pH, requiring DAVIES "pH PLUS" treatment.  Consult the pool test kit after cleaning to ensure proper pH.  Under use, dilutions and normal contact time 
(5 minutes) DAVIES "POOL-KLEEN" has no adverse affect on concrete or grouting.  However, if used as is or spilled, etching may occur with prolonged contact time.  Rinse well with water immediately to prevent concrete etch.