Hydrometer help

[cdn_beaver]

I have a hydrometer/thermometer, that floats in the tank, and works alright, but is hard to accurately read, so I decided to try a different style of hydrometer. I picked up an Instant Ocean hydrometer exactly like the one pictured. Problem is, when I tried it, the reading seems to be way off. My old hydrometer read 1.022, but the new one reads 1.028. My tap water reads 1.013! Has anybody else had any experiences with these hydrometers? Im not sure wich one to believe.

 

[salty cheese]

From my own experience swing arms are very inaccurate. When I checked my salinity with a refractometer it was off by 4 ppt.

 

[rhanes22]

I too disbelieve my hdrometer sometimes. But I have worked with a couple and they all seem to vary. There are also many variables that affect the actual reading. I read in a book that what the hydrometer and what the actual salinity is is off by a considerable amount, almost .008 in some instances. Also at different water temperatures you will get a different reading. When water is heated, molecules are more active and move, thus giving you a different reading than if it were cooler when molecules are in an inactive state. So keep that in mind. Also dont forget to rinse your hydrometer after every use. It may sound miniscule, but is important on getting the most accurate readings using your hydrometer.