I was hoping someone can answer my question. Before I went BBB the pool store told me to put 2 1/2 16 oz. Biogard Scale Inhibitor into my pool. My guess is because my CH was pretty high. My trusty TF-100 measured my CH after I put the scale inhibitor in at 630. The ingredient is 2-phosphono-1,2,4-butanetricarboxylic acid. Does someone know what this is supposed to do? Reduce scaling? I am not about to buy this again I'm just curious.