Good points made. I think I am going to put this one to the test. I have some Tums upstairs. I am going to put it into a glass of my tank water and see what happens. Just for S and G. OMG, back to chem lab. I have not tested the Ca++, but I have been using Reef Crystals for my salt mix. I should be around 400. Reeron: Yup, that could have an effect, but I would be willing to be that the system is not saturated. Thus, it would only slow the reaction, not impede it totally. A reading of 450 is optimal if I am not mistaken. Readings of 600 have been reported on the threads and there has been no crystalization. And there is no CaCo3 in the system. There is Ca++ cation and carbonate anion as well as bicarbonate, which would point the vector back in my favor: DISSOLUTION!!!!! Hehehe. Phayes: No doubt that pH plays a part in dissolution of ionic compounds, but the difference between 7.0 and 8.0 is only 10x change. I can still play devil's advocate on that one.