Hanna salinity vs refractometer

[NormanB]

Like the title says...salinity got too high and now slowing bringing it down. I was only using the Hanna for the last few years, but the reading was high (37ppt) I got out the refrac to check.

Hanna was calibrated with their standard that is still within its expiration date. Checked again after calibration and still 37ppt.

Got out the refractometer calibrated to 0 with rodi then with 35ppt calibration solution which is within its expiration date and tested

Salinity was almost 40ppt.

Darn

Granted the Hanna at 37ppt could be 36-38ppt I still don't like the difference.

For now I'm lowering salinity slowly and averaging the 2 readings.

Any suggestions?

TIA

 

[biophilia]

Every single Hanna salinity monitor I have ever used (including 5 of the HI981520 Marine Monitors) and at least 6 or 7 of the handheld salinity checkers has consistently read 2-3ppt lower than calibrated refractometers. At the public aquarium I work at we check them weekly against a calibrated lab grade Thermo-Fisher salinity meter and they’re always off. I will say that they rarely drift out of calibration, so as long as you mentally adjust for the difference and shoot for 31-34ppt they are worth using.

It is frustrating because Hanna refuses to acknowledge the ongoing inaccuracy of their calibration packets.

 

[Salty_Northerner]

I also use the Hanna salinity checker in PPT and the Hanna fluid is off. I found that using the Neptune salinity solution is bang on to the analog TM floating hydrometer after calibration.

 

[jimk60]

I gave up on my Hanna salinity tester a long time ago. Trusted it for too long with regular calibration and it was off.

 

[exnisstech]

I'm on my second Hanna which isn't any better than the first. Total garbage IMO. Back to using a refractometer and TM hydrometer for double checking.

 

[Devisissy]

Just use a hydrometer then calibrate the refractometer to that once a month. Problem solved.

 

[NormanB]

Thanks all for your comments and experiences.

I hadn't heard before that Hanna has issues with their calibration fluid.

I'll put the Hanna to the back and continue with the refractometer.

 

[Randy Holmes-Farley]

Thanks all for your comments and experiences.

I hadn't heard before that Hanna has issues with their calibration fluid.

I'll put the Hanna to the back and continue with the refractometer.

You can make calibration fluids for both the Hanna and a refractometer (and a hydrometer) here:

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com