Apex Salinity Probe VS Hanna Salinity Tester

[AdamNorris]

Has anybody ever had any issues with the Apex Salinity Probe being accurate? I just calibrated it last night as I filled my tank. It shows 34.4 right now, but the Hanna says 39.9 measures right next to the Apex probe in the sump? Im sure the Hanna would be more accurate but that’s a HUGE difference

 

[Jbell370]

I calibrate the Apex probes every 30/60 days. Has been actually reliable and I verify it with a Milwaukee salinity test.