Problems With Salinity Reading

[Cory-girl]

Can anyone tell me if they have ever encountered this problem and if there is a correct solution?


My husband purchased a Coralife Deep Six Hydrometer to read the salinitiy in the tank. We later purchased a Refractometer, Model RHS-10ATC, for a more accurate reading. We found there was always a difference between the two. My husband contacted Coralife and they sent him a replacement hydrometer. Now, after testing the water in the tank, he has found that both the old and the new hydrometer read .027.


The refractometer gives us two different readings depending on what calibrating solution we use.




Refractometer Calibration Solution .022 (recommended by our LFS)
Distilled Water .028 (recommended by Manufacturer)




We are completely confused and unsure as to what is the correct reading. :confuse:

Anybody has any advise? We would greatly appreciate it.

 

[-Logzor]

Hydrometers are notoriously inaccurate, so I wouldn't use them as a guide. On the other hand, refractometers can be just as inaccurate if they are not used / calibrated properly.

You need to calibrate for values closest to those that you will be testing, so you should only be using the calibration solution, not distilled water.

Float the calibration solution in your tank water until the temperature matches.

Don't try to use a refractometer in a cold environment if it has an automatic temperature compensation feature. Needs to be room temperature, around 70 degrees.

Let the sample rest before trying to dial in the calibration.

I ended up switching to a conductivity probe due to these types of issues. The temp. compensation on my screwed up and my salinity became way too high...