i MOVED IN MY HOUSE IN THE WINTER TWO YEARS AGO AND THE PEOPLE WHO LIVED HERE DIDN'T EVEN CLOSE THE POOL UP AND WHEN WE LOOKED AT IT THE POOL WAS A DARK GREEN AN VERY SCARY . WE WOULD TEASE ABOUT ALLIGATORS BEING IN THERE. ANYWAYS MY POOL IS ABOUT 24' ROUND ABOVE GROUND WITH A CARTRIDGE FILTER AND A 3/4 HP PUMP. fIRST THING FIRST WHAT SIZE POOL DO YOU HAVE ? IS IT ABOVE GROUND? VINYL LINER? i STARTED OFF WITH ABOUT 6 - 1 LB BAGS OF SHOCK . LET THAT SILTER FOR ABOUT 24 HOURS . GO GET A TEST KIT AT WALMART THAT USES DROPS NOT STRIPS AND FOLLOW THE DIRECTIONS OF CHECKING THE CHEMICALS LIKE PH AND CHLORINE , ALKANITY. PH SHOULD BE BETWEEN 7.2 AND 7.4 TO GET THE CHLORINE TO WORK PROPERLY. IF THE PH IS BALANCED THAN FOR NOW MAKE SURE YOU KEEP THE POOL ATLEAST 15PPM OF CHLORINE UNTIL YOU SEE A COLOR CHANGE . FILTER , FILTER AND FILTER THAT WATER . LET ME KNOW WHAT MORE QUESTIONS YOU HAVE