The term given to the calcium particles that appear after the pool has been plastered and filled with water. The correct term is "Calcium Carbonate Precipitates". These precipitates are always white, even in colored plaster pools. These particles are most of the main reason for the required brushing of the newly plastered pool 3 times daily for the first 2 weeks after being filled. The plaster cures underwater and if these particles (or anything else for that matter)are allowed to settle on the fresh plaster too long (8 hours is a common estimate for maximum time), they bond with it and create problem rough spots.