conductivity and salinity the same?

[LEGENDARY_ENG]

Hello just wondering if conductivity and salinity are measured the same? thanks

 

[plyr58]

Conductivity is a measurement of a material's ability to conduct an electric current. Salinity is a measurement of the dissolved salt content in water. Specific gravity is the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure.

For our purposes, the end result of all three is the same. It gives us a value of how salty our aquarium water is. The units for conductivity, specific gravity, and salinity are different, but some conductivity meters marketed towards saltwater aquariums even convert units to give you a specific gravity or a salinity reading.

 

[paraletho]

I use dissolved oxygen/conductivity/salinity multi-meters at my job and most meters measure conductivity and through a formula convert to salinty. So yes they are the same with different units of measurement. When dealing with saltwater.

 

[bertoni]

These days, salinity is defined in terms of conductivity, so they're very closely related.

 

[Randy Holmes-Farley]

i discuss such issues in these articles:

Using Conductivity to Measure Salinity
http://www.aquariumfish.com/aquariumfish/detail.aspx?aid=1804

Refractometers and Salinity Measurement
http://reefkeeping.com/issues/2006-12/rhf/index.php

Temperature Corrections for Hydrometers
http://reefkeeping.com/issues/2004-07/rhf/index.htm

Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm

Specific Gravity Measurement
http://www.advancedaquarist.com/2002/1/chemistry

 

[LEGENDARY_ENG]

Thank you Very useful information just what i wanted to know. Do you know of a calculator that you can enter temperture and conductivity to get salinity? or a formula Thanks steve

 

[therealfatman]

There is a calculator at ths link.

http://www.fivecreeks.org/monitor/cond.html

 

[Randy Holmes-Farley]

There is something wrong with that calculator, so I wouldn't use it. It says normal 35 ppt seawater at 53,000 uS/cm and 25 deg C is over scale.

Salinity is linear with conductivity. So for a reef tank, which will be near 35 ppt and 53 mS/cm, you can essentially just multiply the conductivity in mS/cm by 35/53 and get the salinity in ppt.

 

[LEGENDARY_ENG]

I found one check this one out
http://fermi.jhuapl.edu/denscalc.html

 

[Randy Holmes-Farley]

That one is fine, but you must enter 25 deg C regardless of the temperature because all hobby meters (and in fact, most professional meters) automatically adjust to the 25 deg C equivalent conductivity. You must also convert mS/cm to S/m by dividing the mS/cm by 10 before entering it.