Specific Gravity / mS / ppt question

[thesmartfisherman.com]

I am involved in a Reef Aquarium hobby. We measure the salt content of our water in a few ways.

The one I use most is Specific Gravity (SG)

Another widely used measurement is Practical Salinity Units (PSU) which was once called parts per thousand (ppt)- This changed since salinity is no longer defined as directly relating to solids in the water, but rather by its conductivity.

All the following are at 25 degrees C

Recently, I bought a calibration liquid for my refractometer that was using 53 mS/cm. Conductivity.

I found the conversion to that as 35ppt and 1.0264 sg.

My question is: Is there something on here that gives this information / conversion?

[JohnS]

There is a thread in the Resource section.

I don't completely understand it, and don't do anything with salinity, so I am afraid you are on your own in judging its merits.

[thesmartfisherman.com]

Thanks JohnS

[Mrs X]

Originally Posted by thesmartfisherman.com

I am involved in a Reef Aquarium hobby. We measure the salt content of our water in a few ways.

The one I use most is Specific Gravity (SG)

Another widely used measurement is Practical Salinity Units (PSU) which was once called parts per thousand (ppt)- This changed since salinity is no longer defined as directly relating to solids in the water, but rather by its conductivity.

All the following are at 25 degrees C

Recently, I bought a calibration liquid for my refractometer that was using 53 mS/cm. Conductivity.

I found the conversion to that as 35ppt and 1.0264 sg.

My question is: Is there something on here that gives this information / conversion?

Hi There! If you want to check it out, a very useful substance is party ice. It is very pure frozen water, and if you let it melt in something really clean (that you have rinsed out several times with small amounts of melting party ice) and allow it to get to 25°C, you can use it to make a more dilute solution with your aquarium water. Do you have any way of getting party ice?

If you use half sea water by volume, and half party-ice water by volume, then your resulting solution should be 17.5ppt, and 1.0132sg. - If you measure the conductivity of this solution, you can make yourself a graph, which should have a linear relationship. You can extrapolate either end of the graph to get to the values you actually need.

Hope the fish are all good.