The most important number is how many gallons of water the pool holds. That is the basis for all chemical additions. Look at the pool packaging and see if it lists the gallons of capacity. If it is not on the box, you must calculate it. Measure the size of your pool and convert all measurements to feet. Multiply length times width times depth. For round or oval pools, multiply that figure by 5.9 for total gallons; for square and rectangular pools multiply by7.5 for total gallons. Write the number down and keep it handy.
Fill the pool with water and test the water for alkalinity, pH and chlorine. A pool water testing kit that uses drops and tests for all three of those items is necessary. The first test to perform is to see how much alkalinity is in the water. The alkalinity should measure between 80 parts per million (ppm) and 120 ppm. If the alkalinity is low, add a small amount of alkalinity increaser to the pool water. If the alkalinity instructions say to add 1 lb. of alkalinity increaser for every 10,000 gallons to raise the alkalinity 10 ppm, pare down the figure based on the number of gallons you calculated. Add the alkalinity in one-third increments with a half-hour interval between additions. Too much added all at once can make the water cloudy. Test the reading between additions to make sure you do not overshoot the mark.
Test the pH and adjust it by using one of two chemicals whose generic names are pH+ and pH-. The ideal range for the pH is between 7.2 and 7.6. When this level is correct, wait until the day's swimming is over, then add a small amount of granular chlorine. Dissolve the chlorine in a bucket and when dissolved, pour it around the inside perimeter of the pool. Test the water after you have put it in and see what chlorine measurement you get. The chlorine reading--since you just shocked the pool with chlorine shock--should measure somewhere around 9.0 ppm chlorine, which is very high. It is necessary to have the chlorine spike that way to kill all bacteria and germs in the water. The shock will burn them up and get rid of them. The sun pulls the chlorine out of the pool, which is why we are doing it at night--that way the chlorine lasts longer. That much chlorine will irritate both skin and eyes, another reason to do it after the kids are done swimming for the day. Remove all leaves and floating debris with a net as soon as you see it. If the pool is treated everyday with a small dose of chlorine, the cleanliness of the water can last indefinitely, but eventually the pool should be emptied, wiped down and refilled with fresh water.