October 2015

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. 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!


The Tropic Marin® MEASURING CYLINDER is available as single item and as set together with the Tropic Marin® HIGH PRECISION HYDROMETER.