The present invention provides chemical-mechanical polishing (CMP) methods and apparatus suitable for polishing a substrate utilizing a low suspended solids slurry composition. The CMP methods of the invention comprise polishing a substrate with CMP slurry containing a low suspended solids level (e.g., about 0.01 percent by weight to about 1.0 percent by weight) of a particulate abrasive material in a CMP apparatus, while continuously monitoring and accurately maintaining a predetermined total suspended solids (TSS) level in the slurry. Preferably, maximum TSS variability of the slurry is less than about 20 percent (i.e., ±20% of the target TSS level), more preferably less than about 10 percent TSS variability (i.e., ±10% of the target TSS level) during the course of the polishing process.