Southdown sand where to buy?

[StirCrazy]

TYPICAL CHEMICAL ANALYSIS OF CRUSHED OYSTER SHELLS
CaCO3 (calculated from Ca) 97.5 %
Boron 1400 ppm
Calcium 39.00 %
Titanium 100 ppm
Silica as SiO2 (calculated from Si)< 0.01 %
Lead less than 15 ppm
Sodium 9200 ppm
Copper 9 ppm
Magnesium 1400 ppm
Lithium less than 10 ppm
Iron 430 ppm
Arsenic less than 2.50 ppm
Strontium 1400 ppm
Nickel 75 ppm
Manganese 430 ppm
Heavy metals as Pb less than 20 ppm
Aluminium 3500 ppm

After seeing the the bags when I used to feed my chickens, yes I grew up on a farm, make your jokes now :D and knowing how dirty it is I would never use it. yes it can be washed but the high level of phosphates is enuf to scare me away.. I might as well be using Calgary water :D
seriously though.. there are a lot of contamanants in crushed oyster shell that washing will not get rid of and that IMHO you don't want in your tank.

Steve