High Quality Refractometer Recommendations?

[painter1982]

I find conductivity meters that have a probe on a cord much more user friendly than either hydrometers or refractometers. :)

Can you point me to your means of calibrating or testing a conductivity meter?

 

[Randy Holmes-Farley Verified Community Expert]

Can you point me to your means of calibrating or testing a conductivity meter?

The logistics depend entirely on the meter, but I make my diy 53 mS/cm (35 ppt seawater) standard, read it with the meter, and set it to read 53 mS/cm or 35 ppt.

Often, I do not bother to recalibrate, but just make the manual correction I show above. I equilibrate my standard (53 mS/cm) in the meter for several minutes (to be sure it is temp equilibrated) and get a reading. Then if it says 52.5 mS/cm, I correct subsequent readings manually by multiplying by 53/52.5

 

[Aspect]

Calibrate it however you want. Then test 35 ppt. If it reads 34 ppt, then you multiply all readings with that calibration by 35/34.

If you use specific gravity, then use the last digits only . For example, 35 ppt is about sg = 1.0264. If it reads 1.025 then multiply all readings by 26.4/25, and put the one in front again.

The only way I can see to calibrate is with distilled or rodi water, id like to calibrate at 35 ppt though

 

[Randy Holmes-Farley Verified Community Expert]

The only way I can see to calibrate is with distilled or rodi water, id like to calibrate at 35 ppt though

I don’t think you can based on the electronics, but what I suggested works exactly like recalibration, except it’s a little more work.

 

[smoorman11]

Any reason to think I shouldn't trust my 20 year old TM hydrometer? Can they go out of calibration? Can the scale move from vibration Etc?

 

[Randy Holmes-Farley Verified Community Expert]

Any reason to think I shouldn't trust my 20 year old TM hydrometer? Can they go out of calibration? Can the scale move from vibration Etc?

It is likely fine unless the paper moved (or was mismanufactured originally). It is easy to confirm it with a cheap DIY standard:

https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

 

[smoorman11]

It is likely fine unless the paper moved (or was mismanufactured originally). It is easy to confirm it with a cheap DIY standard:

https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

Will do. Thanks

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing. :)

 

[X-37B]

I have used the TM for quite awhile. I use my conductivity meter now and use the TM to check it.
The two units are within 0.0003 of each other.
Not sure why more people are not using these over other methods.