Your quoting an article by Ron Shimek, who is the most biased person available to comment on DSBs. Many qualified chemists have talked about substances binding to calcerous substrate. An example is the use of kalk to precipitate PO4 from solution. And since Ca is a cation and PO4 an anion, the relationship is obvious. To break this bond would require something with a stornger charge, like HCL. However, although a bath in HCL would remove the PO4, the size of most sugar sands would lend itself to complete dissolution in the time required to cleanse it. Large crushed coral can be successfully washed in acid.
Further "proof" for me is the fact that I had removed some of my sand, cleaned it, and replaced it back in the tank. ALmost immediately it started growing algae again. I believe this algae growth is due to the presence of PO4 adsorbed onto the sand.
As a note, I now have a 1.5 inch sandbed and no detectable nitrates present.
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Brad
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