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.
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.