Scott --- you don't say how big your pool is so it is hard to suggest an amount. But to give you some idea --- I have a 24ft AG, a 1/2 hp fullrated inground pump and a 200 lb. sand filter. I usually start out with adding about 1/4 of a cup of DE and then go from there. The first time I did it, I didn't see a 1 psi rise, so I added more and then it was too much. After that, I learned that you have to wait a bit --- maybe even 1/2 hour to see the increase in pressure, so be patient and don't add any more until you give it a little time. If after 1/2 hour, no psi increase, add just a little more. You'll soon learn how much you need after a couple of tries.