Saltwater
AccuraSea Seawater Reference & Calibration Solution
Star rating
4.6/ 5
Customer reviews
12
- 5 stars 10
- 4 stars 1
- 3 stars 0
- 2 stars 0
- 1 star 1
Brand
Two Little Fishies
Product description
What it is
A single bottle of Seawater Reference and Calibration Solution made from genuine seawater, prepared specifically for instrument calibration. The formula preserves the natural balance of dissolved salts so devices read as they would in real ocean water.
How it's prepared
The liquid begins as natural seawater that is micron-filtered to remove particulates and UV-sterilized to reduce microbial load. After treatment, it’s blended with reverse-osmosis water to achieve a standard target salinity of about 35 ppt (roughly 1.026 specific gravity) and matched to common conductivity benchmarks used in marine aquaria.
What’s included and size notes
Each purchase supplies one sealed bottle of reference solution intended to serve many calibration cycles. The container holds enough liquid for repeated refractometer and hydrometer checks; users who perform routine calibrations or have multiple instruments will typically get long-term use from a single bottle.
How to use it
Bring the solution to the same temperature as the water you’re measuring for the most accurate result. Apply the recommended number of drops to a refractometer prism or use it to verify a swing-arm hydrometer. The solution may also be used as a comparative standard when assessing commercial seawater test kits because it contains the correct proportions of natural dissolved salts.
Care and handling
Keep the bottle sealed when not in use to prevent evaporation. Many aquarists puncture the thin inner film with a pin so the bottle can function as a controlled dropper; this minimizes exposure while allowing easy application. Store away from direct sunlight and extreme heat to preserve stability.
Pros
- Prepared from actual seawater for realistic ionic balance
- Micron-filtered and UV-sterilized for stability
- Suitable for refractometers, hydrometers, and test-kit comparison
Cons
- Single bottle may be larger than some users need
- Seal needs careful handling to avoid evaporation
- A few users report inconsistent readings with specific instruments
VerdictAccuraSea provides a natural seawater-based calibration fluid designed to give hobbyists and technicians a consistent reference point for salinity instruments. It’s made from real seawater that is micron-filtered and UV-sterilized, then diluted with reverse-osmosis water to a target salinity of 35 ppt (approximately 1.026 SG) and aligned with common conductivity standards. Use it to set refractome
Customer reviews
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Leah M. 5/5
Exactly as advertised
Reads right at 35 ppt (≈1.026) for me. I tried other brands that missed the mark; this one matched expected values every time.
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Paul V 1/5
Didn’t match my other solution
I compared it to another brand and this showed much higher on my refractometer. It read about 42 ppt while Brightwell read 35. Ended up discarding it due to the discrepancy.
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JD 5/5
Trustworthy accuracy
Very precise for calibration. I recommend puncturing the foil to limit evaporation. Matches lab ICP checks we run quarterly.
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steve barnes 5/5
No surprises
Performs as intended with no issues.
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christian t. 5/5
Straightforward and effective
35 ppt reference for calibrating refractometer — works fine and is straightforward to use.
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Sharon 5/5
Confirmed my readings
Verified my refractometer was still in spec after only using RO for prior checks. Small investment for confidence in salinity.
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max 5/5
A staple for my setup
I keep two inexpensive refractometers and recalibrate often. This solution verified another brand I tested and I’ll keep using it for routine checks.
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Steve G. 5/5
Essential for accurate salinity
Needed for reliable calibration. Shake well before use and enjoy worry-free checks.
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Frugal 5/5
Keeps my measurements consistent
Longtime reef keeper here — I use this regularly. Always float the solution to tank temp first, clean the prism, then use three drops of RO to zero the scope before checking with AccuraSea.
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E. Thompson 5/5
Very reliable across instruments
Tried several calibration fluids; this one consistently read at 35 ppt on multiple refractometers I used.
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Felic 4/5
Good product, wish it came smaller
Calibrated my refractometer with this and it was correct. I poked the seal and stored in a ziplock. Four stars because the bottle is larger than I need.
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Adrian Henson 5/5
Handy tip inside
Great for confirming refractometer accuracy. Punch a tiny hole in the seal so the bottle can act as a dropper — less evaporation and easier application.
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