Faulty refractometer?

[Xj reefing]

I bought a dymax refractometer today and I keep getting heigh readings of 1.30 even when I test the lfs water that some corals came in. It is calibrated correctly. Is there any tricks to using this or could it be faulty?

[M. Tournesol]

My aqua medic refractometer was also faulty when I go it. When calibrated with RO-DI water, I have an error of +0.1 . My trick for using it was to calibrate it to 1.25.

[Firefish15]

Yeah, I’d buy a small bottle of refractometer calibration solution to check it against. Just a few bucks, will last you forever, and gives you that peace of mind.

[seabass]

4 hours ago, Xj reefing said:

It is calibrated correctly.

Sounds like it's defective.  IDK, maybe dropped in shipping at some point.  I'd exchange it for one that works.

[DaJMasta]

Worth mentioning that many LFSs still use hydrometers for saltwater measurement, which can easily be that far off (presuming you mean 1.030, a specific gravity of 1.3 is higher than the saturation point of water).  I'd second trying to get hold of a calibration solution (usually only a few bucks and you only need drops each time) and checking it before returning or similar to be sure it's both faulty and can't be calibrated.

Worth mentioning that many LFSs still use hydrometers for saltwater measurement, which can easily be that far off (presuming you mean 1.030, a specific gravity of 1.3 is higher than the saturation point of water).  I'd second trying to get hold of a calibration solution (usually only a few bucks and you only need drops each time) and checking it before returning or similar to be sure it's both faulty and can't be calibrated.

[ef4life]

Get a hydrometer and never look back. A little fragile but no calibration needed. Just set it in water and read the salinity 

[M. Tournesol]

45 minutes ago, ef4life said:

fragile

🤣 I broke my first one 5-6 months after buying it. Looking at this topic reply, it seem that I also have a faulty refractometer. Luckily I bought a second hydrometer.

I must be cursed 👻

[DaJMasta]

Hydrometers are notorious for their inaccuracy because buildups of gunk on them (or even just bubbles in the sample) can produce false readings, not that they can't work, but their reliability is probably an order of magnitude or more worse than a refractometer... and the sort of drop that would damage one would like drop the other.

If you take care to keep a hydrometer clean, inspect it before use, and are consistent about using it properly, it certainly works, but personally I would never recommend one over a refractometer.

[M. Tournesol]

we don't speak of the same hydrometer.

[DaJMasta]

Yep, I'm talking about the swing arm variety.  Worth mentioning that neither type of hydrometer will do temperature compensation, but so long as your temperature when measuring is fairly consistent and the unit is clean, that variety should maintain accuracy.  Depending on its initial design calibration, normal tank temperatures will likely mean that the actual specific gravity is slightly higher than what it measures (most are calibrated to cooler temperatures than we run our tanks).

[M. Tournesol]

1 minute ago, DaJMasta said:

most are calibrated to cooler temperatures than we run our tanks

mine is calibrated for 25°C (77°F)

[Xj reefing]

Update: the refractometer is not faulty I just did not allow the water and refractometer to become the same temp. My salinity is high so I am working on that

[seabass]

That's good that it's working.  Is this a temperature compensating refractometer?

http://reefkeeping.com/issues/2006-12/rhf/