How does everyone measure salinity?

[dtdream]

Hi guys, just wanted to take a poll on how does everyone measure salinity? 

Hydrometer, refractometer and/or digital units like Hanna/Milwaukee? How is your experience with your respective device?

I’m personally using a refractometer from FnM, but I’m starting to question its accuracy. Eg. Exact same tank water or separate calibration fluid will measure slightly different salinity (33ppt vs 35ppt) at different temperatures. It’s supposed to be ATC (auto correct), but doesn’t seem to be working as it’s supposed to be.  
 

Thinking of getting another refractometer (eg. DD) or another type of salinity measurement device. 
 

Can anyone share their experience and if anyone is using more than one type and care to share which seems to be a more accurate device and why?

[Reza San]

I'm using refractometer. Bought calibration fluid to calibrate them. Only to realise RO water works just fine. As long your corals are doing fine it shouldnt be too much of a problem.

I always aim for 1.0255 to give room for errors.
I do have an ATO as well to compensate for the evaporation. As and when, I will just get hold of the refractometer and check the water again to make sure all is good. Just ensuring stability is in check.

Had friends who uses Milwaukee ones. Extremely faster and those digital ones are easier to read. (Doesn't require squinting your eyes).


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[josephwzr]

I’ve heard that calibrating your refractometer to calibration solution is more accurate than RO water.

For calibration solution like TLF Accurasea, you’ll be calibrating the refractometer against 35ppt salinity. Whereas if you were to calibrate against RO, it’ll be 0ppt.

[dtdream]

Hi guys! Thanks for your responses. Yea I did buy a calibration solution (brightwell). But even so, using the same calibration solution, at different room temperatures (aircon vs no aircon), my refractometer is giving me different salinity values (about 2 ppt difference which is too big difference imo). My refractometer is supposed to be auto temp correct, but just doubting that now.

Thinking of trying another salinity measurement device but wondering if I should get another refractometer, or another type of device altogether (eg. Hydrometer/Hanna/Milwaukee). But I'm not sure which is "most accurate", and preferable "most consistent" as well.

 

[Reza San]

Those devices need to be calibrated as well. It's the same. The solution is to be consistent when checking. If you're checking in a non-aircon room, keep doing it in the future. If you're done checking, have some RO water ready to dab it on the refractometer and clean the prism glass.