Refractometer comparison

[ssgatbliss]

So I have a RHS-10ATC refractometer and I've been very happy with it for years. I recently read where the new DD H2 Ocean refractometers are more accurate for SW because they take into account all the other elements in it. While cruising my LFS they had one so I picked it up. Same basic principle, calibrate with RO-DI and you are good to go.

To my surprise the old RHS reads a full 2 PPT % less then the DD H2. Guess that explains some of the low readings I was getting when mixing saltwater.

On the downside the new DD is much harder to read due to the smaller display than the RHS and it seems to need a brighter light source. Then again that could just be my eyes going bad as I get older. The viewing area seems to be the same but the markings on the DD are much smaller and only use about half of the provided area available compared to the RHS.

 

[NWDiver]

Careful SSG, You should not be calibrating refractometers with RO/DI water. You should use a solution that is much closer to salt water. There is a good Randy Holmes-Farley article on this issue.
Most folk use Pinpoint 53.0mS calibration fluid.
Lemme see if I can find the article... Here ya go Refractometers and Salinity Measurement by Randy Holmes-Farley - Reefkeeping.com

-Todd

 

[mcoomer]

Yeah, I'm still surprised at the number of companies that still instruct users to calibrate using RO. I use the 35 ppt cal solution that came with my salinity probe to calibrate my refractometer. You really should use a reference standard to do your cal.

Mike

 

[NWKENPO]

Hi new here so please bear with me Im looking for a good refractometer , what is the best one out there and where can i get it? Thank you