Hikari AccuProbe Hydrometer

The Hikari AccuProbe Hydrometer is the fast, affordable way to check the salinity and specific gravity of your saltwater or reef aquarium. Just fill, read, and go. The clear chamber and easy-to-read swing needle give you an instant measurement with no batteries, calibration fluid, or guesswork required.

Why the AccuProbe

• Instant specific gravity and salinity readings in one tool
• Highly accurate swing-needle design that is easy to read at a glance
• No batteries or power needed, ready whenever you are
• One-hand fill chamber for quick checks during water changes
• Durable, rinse-and-reuse build for everyday marine and reef use

How to Use

1. Dip the chamber into your aquarium or a sample of tank water and fill it.
2. Tap the side gently to release any air bubbles clinging to the needle.
3. Read the value where the needle settles on the scale.
4. Rinse with fresh water after each use to keep readings accurate.

Most reef and marine aquariums target a specific gravity of about 1.024 to 1.026 (roughly 35 ppt salinity).

Specifications

Dial In Your Salinity

Mixing your own saltwater? Pair the AccuProbe with a quality salt like Aquaforest Reef Salt or Waterbox Reef Salt. Want lab-grade precision? Step up to a saltwater refractometer or the Hanna HI96822 digital refractometer, and keep any meter honest with the Brightwell Calibration Standard.

Find more in our Saltwater collection and Water Testing Kits and Instruments.

FAQ

What salinity should I keep?
For most reef and marine tanks, aim for a specific gravity around 1.024 to 1.026, or about 35 ppt.

Hydrometer or refractometer?
A hydrometer like the AccuProbe is quick, affordable, and great for routine checks. A refractometer is more precise and worth adding as your reef matures.

How do I keep it accurate?
Rinse with fresh water after every use and remove any bubbles before reading. Replace the unit if the needle becomes stuck or coated with salt creep.