Tropic Marin High-Precision Hydrometer with Measuring Cylinder

Precise specific gravity readings, with the cylinder to take them in. This kit pairs the Tropic Marin High-Precision Hydrometer with Tropic Marin's matching measuring cylinder. Specific gravity is one of the most important water parameters in a saltwater tank, and many animals are sensitive to even small changes, so it pays to measure it accurately. The transparent cylinder has a stable base and a spout, and at 36 cm (14 in) tall it is sized for taking readings with the hydrometer. Already have the hydrometer? The Tropic Marin Hydrometer is also sold on its own. Browse more water testing.

What's Included

• Tropic Marin High-Precision Hydrometer
• Tropic Marin Measuring Cylinder (transparent plastic, stable base, spout, 36 cm / 14 in tall)

How to Measure

1. Fill the measuring cylinder with no more than 400 mL of saltwater at 25 °C / 77 °F.
2. Make sure the hydrometer is dry and clean, then gently place it in the water until it floats freely.
3. Read the specific gravity on the blue part of the scale at the level of the water surface, not at the meniscus, which creeps higher at the edges.
4. Rinse the cylinder well with fresh tap or RO water after each use to remove salt residue that could throw off future readings.

Temperature matters. Specific gravity drops as temperature rises, so the water should be at 25 °C / 77 °F for a correct result.

Specifications

FAQ

What specific gravity should my reef be?
Natural seawater at 35 ppt is 1.026 at 25 °C / 77 °F. Tropic Marin recommends 1.025 to 1.027 for aquarium water, depending on the type of tank.

Why does the water temperature matter?
Specific gravity decreases as temperature increases. Measure at 25 °C / 77 °F so the reading matches the hydrometer's scale.

Where do I read the scale?
At the flat water surface, not at the meniscus where the water curves up the glass.

How is this different from the hydrometer alone?
This kit adds Tropic Marin's measuring cylinder, so you have a steady, purpose-sized vessel to float the hydrometer in. The hydrometer by itself is also available.