Now, that stuff just plain cracks me up. They take cal-hypo, put it in a bottle, and call it "instant liquid chlorine." I looked at that; not such a bad deal - at wal-mart anyway - $21 for 4 lbs of 73% cal-hypo. Pretty good if your calcium's low enough you need some more calcium, or at least your pool can take more calcium. Just be aware, in spite of what they say, it's not "instant liquid", it IS cal-hypo, and puts calcium in your water!