Hydrometers not even close

[bobnicaragua]

Coralife hydrometer = 1.030
Instant Ocean hydrometer = 1.026
BRS spectrometer = 1.028

Going with the calibrated spectrometer, but I'm really surprised with this much variation in the hydrometers.

 

[P-Dub]

Hydrometers are notoriously inaccurate. Refractometers are the way to go. Just an FYI, calibrate it before EVERY SINGLE USE. Label the most accurate of the hydrometers reading after comparing to the refractometer and note that as the correct level. JIC the refractometer breaks.

 

[Spieg]

Swing arm hydrometers are not great as you have discovered. The glass bobber type are considerably better (better than a refractometer even since they require no calibration). The down side of course is that they can be fragile so you need to handle them carefully.

 

[Scorpius]

Tropic Marin hydrometer is what you want. BRS has it in stock currently.

 

[bobnicaragua]

I've been using hydrometers since the late 90s. My salinity has probably been all over the place!

 

[hawk82]

I use an Instant Ocean hydrometer, its right with my LFS when they checked my water with a refractometer. When Marine Depot had the big sale, I picked up a Coralife hydrometer to have a back up. Well its way off, my Instant Ocean reads 1.025 and Coralife reads 1.028

 

[Gqch]

most of Hydrometers are inaccurate, i have 4 of them collecting the dust now lol, brs Refractometers and redsea refractometer are much more accurate.