Digital Salinity Meter vs Floating Arm Hydrometer

[TheChad]

Hey all,


I have a floating arm Hydrometer, and a Digital Salinity meter. I use to have a refractometer but it broke.

The Digital Meter says my tank is at 1.023 SG, the Floating arm Hydrometer says it is at 1.029 SG.


Which one do I believe? The digital Meter says its more accurate than refractometer's. But how do i know? The meter comes with a 30ppt calibration solution, and the meter shows 30ppt when put into the calibration solution.

Thanks,

-TheChad

[roka64]

That probably sounds about right. The difference between my refracto and hydro was .050. Check your hydro by using distilled water, at room temp and see where 0 is. Those hydros tend to swing with the current and a whole bunch of other variables.

[TheChad]

Originally Posted by roka64

That probably sounds about right. The difference between my refracto and hydro was .050. Check your hydro by using distilled water, at room temp and see where 0 is. Those hydros tend to swing with the current and a whole bunch of other variables.

What really makes me think is that If i remember correctly my old refractometer and hydrometer, where very close in their readings.


Distilled water, is that like RO/DI water?

With regular tap water, the hydrometer shows 0.00


So I should trust the Digital meter over the hydrometer?

Thanks,

-TheChad

[Jarred Darque]

I would trust the digital. IME, albeit short experience, hydrometers need to be rinsed and cleaned often to prevert errant readings. Plus teh arm can trap very small air bubbles, which will also give an errant message.

[Finatic]

Trust the probe. Hydrometers are notoriously inaccurate.

[melosu58]

I have to agree trust the probe

[Sadielynn]

forget the probe I had a digi-lab it was so inaccurate that I got a hydrometer . I fount that it required frequent calibrations and alot of times it was still off ..... So much so that I got a second one and it too had the same issues . It was always off 2-3 points from the refracometer . There are refracometers that are on the market for less than the digi lab and more of a reliable source than either
this is the one we use and have found it quite accurate to other refracometers and I like it since it is easy to use


http://www.premiumaquatics.com/Merch...ode=Hydrometer

[roka64]

That is the same one I use and I love it!

[TheChad]

How do you really know it's accurate though?

That is my issue... No matter which device I have... How do i REALLY know its accurate?

With the hydrometer reading upward of 1.030 or higher, and the digital meter showing 1.023, What is the hydrometer is actually the one that's right? Then I could potentially kill my fish...

This is my problem. I need to figure out how to find out what is really right, so i can make sure my tank is good.

-TheChad

[melosu58]

You know it is accurate by your calibration results. If you calibrate it to RO/DI or distilled or just plain RO water you will calibrate your refractometer to 1.000 which is the true salinity of FW. Once that is correct then your salinity will be right.