Description
Tropic Marin High Precision Hydrometer
Product description
The salt content in saltwater is usually measured as specific gravity (also sometimes called relative density) and is one of the most important water parameters. Many tank inhabitants are sensitive to even minor changes of the water conditions. These should therefore be kept as constant as possible in the optimum range for each tank.
The specific gravity of natural seawater of 35 ‰ (psu) is 1.026 – compared to water measured at 25 °C / 77 °F. Our recommendation for aquarium water at 25 °C / 77 °F is 1.025 – 1.027 (depending on the tank type). For an exact, reliable measure of the specific gravity, we recommend to use the Tropic Marin® HIGH-PRECISION HYDROMETER.
Measuring and reading the specific gravity on the scale of the hydrometer will be easy with the new Tropic Marin® MEASURING CYLINDER ( not included). The high-quality plastic measuring cylinder is transparent, has a stable base and a spout. With a height of 36 cm (14 inches), it is ideally suited to determine the specific gravity using the Tropic Marin® HIGH PRECISION HYDROMETER. It is no longer necessary to switch off the flow pump for a measurement in the aquarium; just take the monitoring of the specific gravity outside of the tank. It is really simple!
Tropic Marin® HIGH-PRECISION HYDROMETER:
• Maximum deviation: 0.001 at 25 °C / 77 °F
• Scale from 1.021 à 1.031
• Resolution: 0.0001
• Recommended range: 1.025 to 1.027 (at 25 °C / 77 °F)
NOTE: The specific gravity is temperature dependent. With increasing temperature the specific gravity decreases. Therefore, the measured water temperature should be 25 °C / 77 °F to obtain a correct result.
• The hydrometer should be dry and clean.
• Gently place the hydrometer into the water until it floats freely.
• Now read the specific gravity on the blue part of the scale of the hydrometer at the level of the water surface – NOT at the level of the meniscus, which is creeping higher at the edges!
• To avoid any distortion of future measurements, rinse the measuring cylinder well with fresh tap or reverse osmosis water to remove salt residues after each use.
We recommend different salinities for various tank types:
Tank type Specific gravity
at 25 °C / 77 °F Salinity in
‰ (psu)
Fish only tanks
(no invertebrates) 1.023 – 1.025 ca. 31 – 33
Reef tanks 1.025 – 1.026 ca. 33 – 35
Shrimps 1.026 – 1.027 ca. 35 – 36