Won't use a hydrometer again!

[jbrady429]

a friend of mine recently bought an Apex controller with a salinity probe and checked his tank water. The hydrometer he had been using showed a specific gravity of 1.026, but the salinity probe (after calibration) showed that the level was 1.037 instead! He bought a refractometer and checked the water (again, after calibration). The refractometer showed a level of 1.035.

We used his refractometer to check the salinity of my tank as well. My hydrometer showed 1.026, but the refractometer showed a value of 1.030!

That's two different hydrometers (I know that mine had been well cared for), both of which were significantly off (in one case, extremely off).

Has anyone else had problems with hydrometers like this? Needless to say, I have already ordered my own refractometer.

 

[den75]

I haven't used one but heard stories similar to yours which lead me to immediately go with the refractometer.

 

[cloak]

Was it a plastic swing arm hydrometer? I've never used one of those before, but I have been using one of those $7.99 floating glass hydrometers for about 17 years now without any problems.

Just out of curiosity though, do either of you have any livestock in your tank? (fish, corals etc) How did they look, being that the salinity was way off?

 

[jeff669]

refractometers are the way to go for sure

 

[Homer Allman]

Buy some calibration fluids and calibrate before testing.

 

[GnarleyMarley]

^ +1 calibrating with ro will get u close but its always better to calibrate to a set number better than zero.

 

[Sabellafella]

Lol i can prob show u 10 years worth of hydros and every single one of them are way way off except one and remember, refract u have to calibrate to temperature and use the same temp water everytime, i kno what my salinity is and use w.e reading off my hydro as that reference

 

[Sabellafella]

You could calibrate with ro but also remember, you measuring for 1.025 so calibration fluid is recommended for pinpoint results

 

[jbrady429]

Great comments, everyone. Fortunately there was no livestock in either tank, but this would explain some livestock loss that my friend had had previously.

They were both the plastic swing arm types--not glass floating hydrometers.

Calibrating a swing arm hydrometer sounds like a good idea, but seems like it would require a lot of calibration solution (i.e. expense). It also doesn't seem like it would be as accurate as careful and calibrated refractometer use.

I'm sticking with a refractometer for now, and possibly a salinity probe down the road.