Is all DE relatively the same? I did not expect to see a white powder when I opened the bag. I purchased "Dicalite" at the dreaded pool store to add to my sand filter, as I was reading the bag it says not to use less than one pound. Of course I read the Pool School article "Adding DE" and it states that you will use approximately a cup or two in most instances. Nowhere near a pound. I searched though a lot of threads but did not really find anything that resembled this. Before I go any further I wanted to run it past the pro's. Thanks in advance.