In all honesty my refractometer was good at the start or so I thought. Even calibration I thought it was good. Turned out I did buy the TM hydrometer and it confirmed to me that the refractometer was way out.I saw the BRS video where Lou Ekus mentions that a hydrometer is more precise than a refractometer since it does not require calibration. I can understand this logic so I wanted to test this theory.
So I had one glass hydrometer laying around that I used before and wanted to test this out. But the results where shocking.
Refractometer showed 35 ( 1026 ), before and after calibration.
Glass floating hydrometer showed 1020
Plastic hydrometer (no bubbles) showed something similar 1021
(everything at 25°C, so 77°F)
Ok, lets assume my I did bad calibration for the refractometer and my salinity of the refractometer is off. So how did I make sure this was not the case.
I got some corals today from a german coral farm and still had some shipping water.
Result: I also tested the corals shipping water (so an external source) and it was almost exactly in line with the results above. Although water was slightly colder.
So I'm not sure what to do now. Pretty sure refractometer is measuring 35 salinity correctly since it showed this result before and after calibration and also for the coral farm water.
But it's hard to believe that both types of hydrometers are off by almost the same value.
I purchased the Hannah salinity tester and that is what triggered everything for me and found out that the salinity was very low compared to my calibrated refractometer. So I pulled some swing arm testers out and went down to my lfs and things seemed to be close. Last night I went down to the LFS and found out that even their equipment was out of whack. The owner got one overnighted and just called me and told me that the TM was reading exactly the same as mine last night. I was literally pulling my hair out not knowing what was right and what wasn't, this tropic Marin hydrometer I put 100% faith into its accuracy.
My Hannah tester is only .01 off. TM shows 1.0255 and the Hanna shows 1.024 so now I can put the fragile one away and do a quick dip with the Hannah tester and know no that everything is chill.