Hydrometer - Am I reading it right?

[kilnakorr]

I did a little maintenance today, and recalibrated my probes.
This resultet in my conductivity probe givibg my 1.023 Sg.
I rechecked with my refractometer, which shown 1.024 Sg.
I dug out a new unused hydrometer, but I believe it shows me 1.020 Sg, or I'm not reading it right. I has som green markings between 1020 and 1025:

I just rechecked an ICP from last month which states 32ppt.

So it does look like my salinity is quite low, but am I reading the above picture right at 1.020Sg?

 

[Pistondog]

Looks like it. Just make sure the hydrometer is free to float.

 

[kilnakorr]

Looks like it. Just make sure the hydrometer is free to float.

It is. Just tried it with RODI water:

Guess it is not accurate at all as it reads 0.997

 

[Pistondog]

Somewhat accurate, it's within 0.3%.
This is a pretty good hydrometer and it specifies within 0.001 at 77f or 25c.
https://www.bulkreefsupply.com/high-precision-hydrometer-tropic-marin.html

 

[Pistondog]

Might try a diy calibration solution
http://reefkeeping.com/issues/2004-06/rhf/index.htm
Also make sure temp is around 25c.

 

[Mr. Mojo Rising]

3 different devices, 3 different readings - that sounds right to me. The best way to maintain sanity is to just pick one tool and stick with it and live and die by it. Even if the tool is slightly incorrect, the tank will adapt and will accept it as the new normal.

 

[kilnakorr]

Somewhat accurate, it's within 0.3%.
This is a pretty good hydrometer and it specifies within 0.001 at 77f or 25c.
https://www.bulkreefsupply.com/high-precision-hydrometer-tropic-marin.html

If the accuracy at 1.026 is between 1.023 and 1.029 it is pretty useless.

Might try a diy calibration solution
http://reefkeeping.com/issues/2004-06/rhf/index.htm
Also make sure temp is around 25c.

I might just try it just for fun