I used 1/2 pack (by weight) for the Intex Prism above ground pool, which is 4ft high by 15ft diameter, and I believe almost 5k gallons of water. I put it in at night.. stirred it around and let the filter run overnight. The water was pretty clear to begin with, but it definitely helped a little with coconut oil residue that was in the water. In addition to this, I also have a chlorine tablets floater. I usually run the filter over night or for about 6 hours during the day.
It last me a long time since I try not to shock too much with powder shock. I like to use liquid instead. Once in a while, in an emergency, when I ran out of liquid I use the powder and it works fine, no complaints. I add it with the pool running, in the very late afternoon, 15-20 min before pump turns off. It dissolves quickly and it works.
I have had a pool for 10 years. I have spent thousands on a variety of chemicals trying to find the best value for my money. Without a doubt, this is the best shock I have ever had. We just opened our pool (27,000 gallons) for the season and it was very green. After dumping the shock directly into the water with the filter on high, it started clearing up within 20 minutes. Now two hours later it is the brilliant blue we love. Highly recommend you stock up on this. Worth every penny!
Product worked better at clarifying pool, and killing some algae forming around the edge of the pool. It turned out way less expensive than at our local pool supply. Packaged very good, and very quick delivery too. Will continue to order here from now on!