Faulty Hydrometer?

[mark]

If you're saying it doesn't swing at all, wet, dry on it's side then the arm is jammed. Unless you can free the arm it's toast and even if you did, I then wouldn't have much faith in it's accuracy.

Exchange it or if you get the arm swinging, do a comparison before trusting it.

As for the swing arm types, used them for years and they always seemed consistent. Thought if they had an error, it would be fixed, read they usually compare within a couple of thou anyways so no big deal if I shoot for the mid point of the salinity range. Then last week was mixing up some change water up and thought was reading low for the amount of salt I added. Checked the tank and it was reading 1.019 which was weird considering I have auto top off, no salt-creep and system (~190g) always reads 1.023-1.024. Ended up getting a refractometer and system was 1.025.

I'd always rise the swing arm hydrometer after use and sure I didn't bang but must have as it had shifted quite a bit (to 0.006 from refractometer). This one was a Coralife Deep Six that been using for more than a year.

[likwid]

The arm is not jammed, it swings if I tilt the hydrometer, but always stays at the bottom when the hydrometer is level, no matter what kind of water is inside or how salty it is.

[mark]

Took a look at my, it's got a white buttom about 1 cm dia that goes through the arm (says Certified Calibration with a number), is that in place on yours?

[likwid]

Yes, it is in place in mine

[mark]

How something so simple could fail..., but looks likes yours is just plain broken.