PAC-LV (Polyanionic Cellulose) is used for fluid loss control, particularly in systems with high salt concentrations or in saturated brine systems. With the same temperature stability as CMC-LV, PAC-LV is generally more tolerant to contaminants than CMC. PAC is used at 0.25–1.0 lb/bbl in freshwater systems and 0.75–3.0 lb/bbl in saltwater systems. To benefit from the cuttings-encapsulating properties of PAC, it must be applied at higher concentrations. PAC-LV is sensitive to calcium contamination, and the maximum calcium concentration should not exceed 400 ppm.