Deep Six Hydrometer — Accuracy ±0.001 Salinity and Specific Gravity 6 in - Coralife

The Coralife Deep Six Hydrometer measures salinity and specific gravity in your marine aquarium with ±0.001 accuracy. Designed to collect a water sample at six inches deep, it avoids hand contamination and delivers a more reliable reading than surface samples.

Key Benefits

• ±0.001 specific gravity accuracy — each unit is individually calibrated and certified
• Samples water at 6 inches deep for a more representative salinity reading
• Integrated bubble diffuser reduces reading errors caused by trapped air bubbles
• Built-in base allows hands-free reading on any flat surface
• Dual scale: ppt (parts per thousand) and specific gravity (range 1.000 to 1.032)

How to Use in a Marine Aquarium

Submerge the Deep Six six inches below the water surface, let it fill, then remove it. Gently tap to release any air bubbles before reading. The hydrometer is calibrated for warm water aquariums between 68 °F and 85 °F (20–30 °C), the standard temperature range for reef and marine tanks. For a reef aquarium, aim for a specific gravity between 1.024 and 1.026.

Technical Specifications

• Accuracy: ±0.001 specific gravity
• Measurement range: 1.000 to 1.032
• Calibration: 68–85 °F (20–30 °C)
• Reading: ppt and specific gravity
• Dimensions: 5.5" x 1" x 8.7"
• UPC: 096316008779

Why Buy This Hydrometer from ReefSolution

The Deep Six is an affordable and reliable tool for daily salinity monitoring. For greater precision, consider the Hanna Marine Salinity Tester HI98319. Pair with a quality salt mix like Red Sea Blue Bucket or Coral Pro Salt to maintain stable salinity. A digital thermometer is also recommended to confirm your water temperature falls within the hydrometer's calibration range.

Frequently Asked Questions

How accurate is the Coralife Deep Six Hydrometer?

The Deep Six is accurate to ±0.001 specific gravity. Each unit is individually calibrated and assigned its own certification number.

At what temperature does the Deep Six give reliable readings?

It is calibrated for warm water aquariums between 68 °F and 85 °F (20–30 °C). Readings outside this range may be inaccurate.

Hydrometer or refractometer: which is better for a reef tank?

A hydrometer like the Deep Six is great for quick, affordable daily checks. For higher precision, especially in advanced reef tanks with SPS corals, the Hanna Marine Salinity Tester HI98319 is recommended.