I made a find! After many unsuccessful trips to HD
, on Saturday I found bags of beautiful pure white playsand called, surprisingly enough, "White Play Sand", brand name is Durascape, part of the Old Castle company. The only mention of sand type says "small amounts silica". Not knowing what the "Large amounts" were, I took it home to do the vinegar test, and lo and behold, bubbles!! It appears to be largely limestone based, so I am going to try it out. Says one bag covers 5 square feet (almost exactly the square feet of a 48 x 18 base tank) to a depth of one inch, costs $3.99. No weight given, so I weighed it myself...47.5 pounds. Good?