The most recommended start up product in the swimming pool industry for plaster pools. The Blue Stuff is very efficient at controlling plaster dust. The Blue Stuff’s proprietary blend removes metals such as copper, iron, and manganese from the water. The Blue Stuff is very stable in high chlorine (even over 10 ppm) levels. The Blue Stuff prevents and removes stains and scale in plaster, vinyl, and fiberglass pools.  1 Quart