Tropic Marin High-Precision Hydrometer The Tropic Marin High-Precision Hydrometer is a precise floating glass hydrometer for measuring specific gravity in saltwater and reef aquariums. Handmade from mouth-blown glass and calibrated for use at 25°C / 77°F, it provides a reliable non-digital salinity reference for reef keepers who want to confirm aquarium salinity, check newly mixed saltwater, or compare readings from electronic salinity meters and refractometers. Tropic Marin High-Precision Hydrometer for Reef Salinity Stable salinity is critical for marine fish, corals, and invertebrates. This high-precision hydrometer gives reef keepers a simple, calibration-free way to measure specific gravity with fine resolution. It is especially useful as a dependable reference tool when checking water-change batches or verifying other salinity measuring devices. Mouth-Blown Glass Hydrometer Measurement Features Designed for determining specific gravity in saltwater aquariums. Handmade mouth-blown glass construction for precise floating measurement. Does not require recalibration like many electronic salinity tools. Fine 0.0001 resolution helps reef keepers read small salinity differences. Blue scale highlights the recommended marine aquarium range. Useful for checking aquarium water, freshly mixed saltwater, and other salinity measuring equipment. Best used in a suitable tall measuring cylinder so the hydrometer can float freely without touching the sides or bottom. High-Precision Hydrometer Specifications Product type: Floating glass hydrometer Application: Saltwater aquarium specific gravity measurement Maximum deviation: 0.001 at 25°C / 77°F Scale range: 1.021 to 1.031 specific gravity Resolution: 0.0001 Recommended marine aquarium range: 1.025 to 1.027 at 25°C / 77°F Material: Mouth-blown glass Country of manufacture: Made in EU Tropic Marin Hydrometer Use Directions Use a clean measuring cylinder or tall test vessel that allows the hydrometer to float freely. Fill the vessel with aquarium water or freshly mixed saltwater at approximately 25°C / 77°F for the most accurate reading. Place the hydrometer gently into the sample and make sure it is not touching the side or bottom of the vessel. Allow the hydrometer to settle vertically and wait for bubbles to clear from the glass. Read the value at the water surface on the blue part of the scale rather than at the meniscus. Rinse the hydrometer with fresh water after use and allow it to dry before storage. Handle carefully because the hydrometer is made from precision glass. What's Included Tropic Marin High-Precision Hydrometer