Huge Difference in Salinity ICP and Home

[chrisd73]

I am more than a little concerned when my ICP came back with my salinity at 31.88 and every refractometer test I do is right at 34. I calibrate it with a 35ppt solution before each use. Should I be concerned?

 

[Aaron75]

I am more than a little concerned when my ICP came back with my salinity at 31.88 and every refractometer test I do is right at 34. I calibrate it with a 35ppt solution before each use. Should I be concerned?

I'd rule out that your calibration solution isn't bad if you're only using the same solution each time.

 

[slythy]

I have found the best way is to get a hydrometer like the tropic marin. It cant be wrong lol. I calibrate my refractometer to that.

 

[Randy Holmes-Farley Verified Community Expert]

I am more than a little concerned when my ICP came back with my salinity at 31.88 and every refractometer test I do is right at 34. I calibrate it with a 35ppt solution before each use. Should I be concerned?

What calibration solution?

 

[chrisd73]

Ok, so I brought in a second calibration solution. Have Fritz and BRS 35ppt. I also bought calibration solution for my conductivity meter and set that. Now after calibrating both my refractometer and conductivity meter, I get 34 on the refracto and 32.9 on my conductivity meter. So which is correct? Or does it really matter?

 

[Randy Holmes-Farley Verified Community Expert]

Ok, so I brought in a second calibration solution. Have Fritz and BRS 35ppt. I also bought calibration solution for my conductivity meter and set that. Now after calibrating both my refractometer and conductivity meter, I get 34 on the refracto and 32.9 on my conductivity meter. So which is correct? Or does it really matter?

I do not know which devices those solutions are appropriate for, but not all solutions are suitable for all devices. So don't mix and match them unless they say they can be.

If you have a decent scale you can make your own and be sure.

 

[Miami Reef]

DIY refractometer solution (35ppt):

Dissolve 3.65 grams of Morton’s Iodized Salt in 96.35 grams (mL) of distilled or RO/DI water.


DIY conductivity solution (53 mS/cm):

Dissolve 1 teaspoon (6.20 grams) of Morton's Iodized Salt in 182 mL (182 g) of distilled or RO/DI water.

Source: https://reefkeeping.com/issues/2004-06/rhf/index.php


If your meter matches the standard, I would be confident that it’s accurate for use.