Salinity test kits ?

[95galReef]

Randy,

Do you know anything about the salinity test kits available?, I know HACH has a titration test for salinityand there are also many others available by other makers also.

 

[randy holmes-farley]

Unfortunately, I've never used one and know nothing about them. Maybe Craig does.

 

[Bob Studt]

The salinity titration kits work by testing for chloride ion and then that chloride level is used to calculate salinity. This is actually the most direct way that I can think of to measure salinity. This only works when the chloride to sodium ion ratio (and the chloride to anything ratio for that matter) is exactly the same as the chloride to sodium ion ratio of natural seawater. For NSW these will work fine but in seawater made with a salt mix this may not always be the case, although in most salt mixes this ratio is close to NSW. If one has been dosing with calcium chloride then that could be another source of chloride to sodium imbalance. I would stick with a refractometer which measures salinity indirectly by refractive index or use a hydrometer and convert to salinity from the specific gravity.


Bob

 

[Anonymous]

hi.
Well, about 4 or 5 years ago, Craig gave me a lesson when I carelessly confused salinity with density. They are not the same thing, and you can't convert one to another unless the ions are in the NSW ratio. Basically, salinity is a chemical property, but specific gravity/density is a physical property. Argentometric titration of Cl- ion is most common test method for salinity, and HACH's kit probably is based on this methodology.

If you like doing titration, salinity test kit may be something you will use. However, there are many easier ways to find out how close your water is to NSW. Conductivity meter and refractometer are some of the accurate methods for measurement of density. Being a careless bump, I just use float needle.

 

[Habib (Salifert)]

If one has been dosing with calcium chloride then that could be another source of chloride to sodium imbalance. I would stick with a refractometer which measures salinity indirectly by refractive index or

The molar refractivity of chloride is 9.3 , sodium 0.46, magnesium 0.24, calcium 1.19 (all at 589 nm).

This means that the refractive index for seawater is relativly far more sensitive to chloride content. Therefore a significant imbalance will result in a false value if a refractometer is used.

 

[AF Founder]

Habib,

Please email me privately; there's something I'd like to discuss with you.

 

[AF Founder]

Habib,

Contact me at

[email protected]

 

[Anonymous]

This means that the refractive index for seawater is relativly far more sensitive to chloride content.

hi.
I guess for accurate salinity measurement, there is no substitute other than a full ICP analysis?

 

[Habib (Salifert)]

I guess for accurate salinity measurement, there is no substitute other than a full ICP analysis

I am not an expert on ICP. I am not sure if Cl and S can be measured by ICP. Even then the error can be quite large.

However if one has highly accurate and precise densitometer, conductivity and refractometers then measuremnent of the same sample with these techniques might give information about any significant ionic imbalance.

 

[rskibum]

That's correct, ICP is only effective at analyzing Cations, I think S with the right plasma conditions, but Cl takes more energy to excite than a plasma is capable of.

But, you could test for all major cations, and from that calculate the total equivilence of salt.

If you wanted to know major anionic constituents as well, you could run it IC.

Ryan