converting ppm to psu

[billsreef]

Seems to be a lack of understanding of what salinity actually is. Salinity is a measure of the salt content and is typically measured via conductivity or chemically by determination of chlorides...after salts are things like sodium chloride, potassium chloride, etc. Things like sulphate, molybdate, etc. have nothing to do with salinity, though they can effect specific gravity. Now in normal seawater salinity and specific gravity happen correlate, so you can infer one from the other. In a tank where you are playing with various things, you can't always infer salinity from the specific gravity as sometimes your ratios of chemicals other than chlorides (salts) get out of whack. So you can't really look at the results of ICP or HPLC components of tank water sample and conclude salinity accurately by adding up components other than salt

 

[billsreef]

PSU is defined in terms of conductivity. I'm confused as to what you're trying to do, too. For our purposes, 35 psu is close enough to 35 ppt at reef conditions, if my memory is correct.

Yup For our purposes PSU = PPT

 

[dkeller_nc]

Salinity is a measure of the salt content and is typically measured via conductivity or chemically by determination of chlorides...after salts are things like sodium chloride, potassium chloride, etc.

Indeed, that's perhaps why the person was telling him that he had to "convert" to sodium chloride. But as you noted, most of us (actually, all of us) assume that our ionic species are at a natural seawater balance, and therefore salinity can be inferred from specific gravity, refractive index, conductivity, etc...

But even if one is solely interested in totaling up the ion concentrations to determine specific gravity (rather than salinity), that's not likely to work well from adding up peak areas/response factors on an ion chromatograph.

 

[Eyore]

Seems to be a lack of understanding of what salinity actually is. Salinity is a measure of the salt content and is typically measured via conductivity or chemically by determination of chlorides...after salts are things like sodium chloride, potassium chloride, etc. Things like sulphate, molybdate, etc. have nothing to do with salinity, though they can effect specific gravity. Now in normal seawater salinity and specific gravity happen correlate, so you can infer one from the other. In a tank where you are playing with various things, you can't always infer salinity from the specific gravity as sometimes your ratios of chemicals other than chlorides (salts) get out of whack. So you can't really look at the results of ICP or HPLC components of tank water sample and conclude salinity accurately by adding up components other than salt

Carry on please

On one level you seem to be inferring that I can't count sulphate but can count mg,ca,k
On another level you seem to be inferring I can count only sodium and chloride
However pretty sure your not infering any of this

As much as anything the 2 parameters I am most interested in are sodium and chloride, as its regarding classic balling method and it's variations, Inc the benefit from the variations. With sodium and chloride of those amounts it's not really possible to see any of this, hense why I query the results