Tropic Marin High-Precision Hydrometer (51001)

Product no.: 00932

PRECISION HYDROMETER -
( precision spindle )
For determination of density in marine aquarium
Product description

The salinity in seawater is usually expressed as density in German-speaking countries and is one of the most important water parameters. Many aquarium inhabitants react sensitively to slight changes in their environmental conditions. These should therefore be kept as constant as possible in the optimum range for the respective tank. Natural seawater with an average salinity of 35 ‰ (psu) has a density of approximately 1.023 kg/l at 25 °C. Our recommendation for aquarium water at 25 °C is a value between 1.022 and 1.024 kg/l, depending on the tank stocking.

The density is to be distinguished from the "specific gravity" (relative density), which is used in the rest of the world. For an accurate and reliable control of the salinity, the Tropic Marin® PRECISION AEROMETER is most suitable.

Measuring and especially accurate reading of density on the hydrometer is now made easy with the new Tropic Marin® MESSZYLINDER. The high-quality plastic measuring cylinder is transparent, has a stable base and a spout. With a height of 36 cm, it is ideally suited for determining the density using the Tropic Marin® PRECISION AFROMETER and for putting the hydrometer down after use. It is no longer necessary to switch off the flow pumps for a measurement in the aquarium; a reliable control of the salinity is now possible at any time outside the tank in the simplest way.

The Tropic Marin® MESSZYLINDER is available individually and as a set together with the Tropic Marin® PRECISION AEROMETER.
Procedure

CAUTION: Density is temperature dependent. As the temperature increases, the density decreases. Therefore, for a correct result, the water temperature should be 25 °C during the measurement.

Fill the measuring cylinder with max. 400 ml seawater (water temperature = 25 °C).
The hydrometer should be dry and clean.
Immerse the hydrometer in the water until it floats freely.
Now read the salinity on the green scale of the hydrometer at the level of the water surface - NOT at the level of the surface skin (meniscus), which pulls up at the edges!
Then rinse the measuring cylinder well with fresh tap or osmosis water to remove salt residues. These could falsify future measurement results.

We recommend different salt contents for different types of pools:
Pool type Density in kg/l at 25 °C Salinity in ‰ (psu*).
Fish only (no invertebrates) 1.020 - 1.022 approx. 31 - 33
Reef aquariums 1.022 - 1.023 approx. 33 - 35
Shrimps 1.023 - 1.024 approx. 35 - 36

*psu = practical salt unit: common measure for the salt content of seawater