Specifically designed for aquarium use for measuring the salinity of
Natural Sea Water (NSW)
Specifications:
Range: Minimum
Division: Accuracy: Light
Source:
0-40 Parts per Thousand of Salinity in NSW
1.00 PPT +/-
1.00 PPT Ambient: Sunlight or Lamp
1.015 to 1.030
Specific Gravity 0.001 SG +/- 0.001 SG
Almost all hand held salt water
refractometers available to the hobby are designed and calibrated for the testing
of brine solutions, i.e. sodium chloride, and are not calibrated for the
refractive index of Natural Sea Water.
This is a very important distinction.
Other Salinity Refractometers used for marine aquariums are designed to
test salt in water – nothing else! The Reef Sea Meter
is designed to measure Salinity of Natural Sea Water taking into account the
other elements that comprise salinity in the marine water sampled.
Even though the largest
percentage of salt in the sea is sodium chloride, the presence of other
significant ions such as magnesium and calcium in natural sea water results in
a different refractive index relative to that of brine. A standard salt (brine)
refractometer will therefore not give the correct salinity for Natural Sea Water
and a conversion factor must be applied.
For
example a 35ppt solution of NSW has the same refractive index as a 36.5ppt
solution of brine. When using a normal brine Refractometer the user should
therefore look for a reading of 36.5ppt when trying to achieve a reading of
35ppt for Natural Sea Water.
EASIER TO READ – MUCH EASIER
TO READ!
One of the other problems with
most Refractometers is that the scale displayed normally reads from 0-100ppt
when we are really only interested in the region from 30-40ppt.
Our The Reef Sea Meter Refractometer
has therefore been specifically designed to read from 0-40ppt which gives you
2.5 times the resolution of a normal 0-100 scale.
AUTO TEMPERATURE COMPENSATION
(ATC)
Salinity is a measurement of a
mass of salt in a mass of water and therefore does not vary with temperature
however a Refractometer does not measure salinity directly but measures the
refractive index which is then displayed as salinity. The refractive index of a
solution does vary with temperature therefore the reading that you measure with
a Refractometer is always temperature dependant.
What people do not generally
understand is that it is the temperature of the instrument and not the water
temperature that is important as the small sample of water used for testing
will equilibrate within seconds to the temperature of the Refractometer.
Once
correctly calibrated at the set calibration temperature of 20’C/68’F the Refractometer
can then be used in environments where the ambient temperature and therefore
instrument temperature would heat up or cool down within the range of the ATC
which is between 10-30’C/50-86’F.
CALIBRATION
If you look at the scale above
you will see that the Refractometer states that it is calibrated at and
displays the SG of seawater at 20’C (68’F). Most salt Refractometers use this
temperature and will be marked 20’C (68’F) or 20/20.
Calibration should always be
carried out with the instrument at 20’C/68’F which is close to the
average room temperature in most cases. Allow the Refractometer to stand at
this temperature for 30 minutes to acclimate.
This allows for the best calibration possible.
The Reef Sea Meter Refractometer is designed with a copper body which is
more expensive to manufacture but responds faster to ambient temperature
changes than other materials.
Step 1: Clean the glass prism
and clear daylight plate cover of the Refractometer with distilled or reverse
osmosis water to ensure that there are no salt residues that would affect the
reading. These water sources will be
pure water with 0ppt.
Step 2: Place a drop of the
calibration fluid (distilled or R/O water) onto the glass prism of the
unit. Close the daylight plate over the
prism and smooth out any air pockets between the prism and the daylight plate.
Step
3: Wait for 15 seconds for the temperature to acclimate with the instrument
before looking through the eyepiece with the prism end pointing towards a
bright light source. The eyepiece can be screwed in or out to adjust the
focus. You will observe that the top of
the view screen is blue and where it changes from blue to clear at the bottom
is where the reading should be taken. If this boundary does not line up exactly
with the zero mark on the scale then take the small screwdriver provided and
having first removed the protective cap adjust the scale position by tightening
or loosening the screw. Your Refractometer
is now calibrated.
PLEASE DO
NOT CALIBRATE WITH 35PPT SALINITY SOLUTIONS AS THEY ARE NOT THE SAME AS NATURAL
SEA WATER!
MEASURING THE SALINITY OF
YOUR AQUARIUM
Ensure that the prism of your Refractometer
is clean by washing the prism plate and cover plate after use each time in pure
water and drying it with the polishing cloth supplied. Why?
The prevent corrosion of the unit and to ensure that your readings are
accurate.
Take a representative sample of
the water from your aquarium or other marine habitat.
Allow the water to acclimate to
the temperature of the instrument for 15 seconds and then look down the
eyepiece to take the salinity reading at the bottom of the blue and clear
interface.
One
side of the scale will allow you to read the salinity and the other side the
specific gravity calculated at 20’C/68’F.
SALINITY AND SPECIFIC GRAVITY
STANDARDS
We recommend that you try to get
used to thinking in terms of salinity and use the salinity readings on the Refractometer
as this is the scale that is calibrated against the refractive index standard.
SALINITY is always constant whereas Specific Gravity, although
more commonly used in the hobby, is fraught with misconceptions that are
explained later.
Salinity as explained earlier in
these instructions is generally described as the mass of salt in a specific mass
of pure water and is normally expressed in parts per thousand or ppt (‰).
For example 35ppt could be 35
grams of salt in 965 grams of pure water or 35 tons of salt in 965 tons of pure
water - 35 units by weight in a total of 1000 units by weight. Weight is never
affected by temperature.
In the oceans the salinity
varies from 5 ppt in the Northern Baltic Sea to 40 ppt in the Northern Red Sea
with a generally accepted global average of 35ppt for NSW. The level that you
keep your aquarium at will generally be determined by the type of animals that
you keep in the system.
Often fish only systems are
maintained at lower salinities down to 29ppt as it exerts less osmotic stress
on the fish whereas reef systems are normally maintained at 35-36ppt.
SPECIFIC GRAVITY is not an exact scale and is defined as the
relationship between the density of a solution, in this case seawater, relative
to the density of pure water – normally measured directly by hydrometer.
As density is temperature
dependant due to expansion, which changes the volume for a given mass, then
specific gravity is also temperature dependant and varies according to two
parameters.
1 - The temperature of the test
sample during measurement – normally the tank temperature at 25’C/77’F
2 – The temperature at which the
pure water (distilled or R/O) density used in the SG calculation was measured
at – normally the calibration temperature that should be printed on all good
scientific hydrometers.
This leads to huge
misunderstandings within the hobby as to what the specific gravity should be
specified at within the aquarium. Most people believe that the SG of 35ppt
seawater is 1.025 at 25’C/77’F whereas in reality the specific gravity measured
is determined by the calibration temperature of the particular hydrometer owned
by the user.
NSW Salinity
Calibration Temp
SG Reading at 25’C/77’F
SG Reading at 20’C/68’F
35ppt
15.5’C/60’F
1.0233
1.0257
35ppt
20’C/68’F
1.0252
1.0266
35ppt
25’C/77’F
1.0264
1.0277
The
specific gravity readings in the table above range from 1.0233 – 1.0277 however
they are all correct in describing the same sample of water at 35ppt salinity.
The difference between the
readings is due solely to the calibration temperature which is used to set the
scale for the instrument.
From this we can see how non
specific S.G. is as a way of describing the salinity of the water in your
aquarium.
The
Reef Sea Meter Refractometers are
calibrated at 20’C/68’F and so the calculated specific gravity at 35ppt
displays a reading of 1.0266. This is the equivalent to a specific gravity
reading of 1.0264 for a water sample temperature of 25’C/77’F using a standard
hydrometer that has a calibration temperature of 25’C/77’F
IMPORTANT! HIGH QUALITY!
EACH UNIT COMES WITH A 3 YEAR WARRANTY AGAINST DEFECTS. FREE REPLACEMENT PARTS IF YOU EVER NEED THEM!
OURS ARE MADE OF STURDY ALUMINUM! A GOOD DEAL IS ONLY GOOD IF THE PRODUCT LASTS AND IF THE SELLER IS STILL IN BUSINESS! WE HAVE BEEN ON eBay SINCE 2001! THAT'S LONGER THAN ANY OTHER SELLER OF REFRACTOMETERS!
GOT A REEF SHOP OR REEF CLUB? BUY FROM US!
YOU CAN CALL, FAX OR E-MAIL US IF YOU EVER HAVE ANY QUESTIONS. CAN YOU CALL OR FAX THE OTHER GUYS ON eBay?
NO ONE HAS SOLD MORE REFRACTOMETERS ON eBay THAN US!
We've been an eBay P Seller for over 10+ years! No one has sold for longer!
Included are: A plastic, foam-lined hardcase, a pipette for dropping test fluids onto the prism (never dip the refractometer into the test fluid!), a mini screwdriver for scale calibration, and a Users Guide.
TO RECAP:
A Great Quality unit
Over 10+ years of selling on eBay! We've seen many other eBay Sellers come and go...
Experienced! Over 10,000 Salinity units sold!
A 3 Year Warranty against defects
FREE replacement parts - no matter where you live in the World!
Customer Service - Call, fax or e-mail us. If we're not available, please leave a message so we can get back to you!
Competitive Pricing
WHY WOULD YOU BUY FROM ANYONE ELSE?
This model sells for $49.95 and up at most retailers. Get yours today at Wholesale prices!
IF YOU WANT THE UNIT WITHOUT THE WAIT, PLEASE CHECK OUT OUR STORE! <---CLICK HERE!
WE HAVE FIXED PRICE ITEMS FOR IMMEDIATE PURCHASE!
CAN'T FIND WHAT YOU NEED? E-MAIL US! WE CARRY MORE REFRACTOMETERS THAN ANYONE ELSE!
BUY WITH CONFIDENCE AND THE PEACE OF MIND!
THIS IS OUR BUSINESS, NOT A HOBBY!
International Shipping:
Shipping is $15.00 ($12.00 to Canada) via US Postal's Global Priority Mail/Air Mail and is advertised as taking 3-8 business days (up to 30 business days!). Please be advised that there can be Customs delays from time to time. These packages come with Delivery Confirmation Numbers only - No Insurance or Tracking Numbers. Excellent value for the money!
Do you want Shipping with Insurance AND a Tracking Number to your International Destination? Please add $25.00 to your order for that upgrade! You'll be upgraded to USPS Express Mail.
Questions? Larger Orders? Please feel free to call, fax or e-mail!
Want it right away? Want more? You can buy them at our eBay Store Listings! Click the tag ------>
Other types of Portable Refractometers are available through our eBay Store!
National Industrial Supply 32483 Temecula Parkway, #E112 Temecula, CA 92592, USA Sales: 310.748.6858 Fax: 310.733.5480 E-mail: chardowner at yahoo.com
We prefer Paypal!
After purchasing, pay instantly with your credit card through PayPal!
Return
Items must be returned within 30 days . Refund will be given as Money back. Refund policy details: null
