EDTA titration is used for all hardness determinations, with a red to the blue endpoint. Both total and calcium hardness buffers include inhibitors to eliminate metal interferences. All results are as CaCO3; some kits also express results as gpg. The 3609, which is recommended for saltwater analysis, includes a conversion factor for Ca++. The -LI suffix indicates an all-liquid kit; -LT indicates a liquid buffer and tablet indicator.