Which to trust? Refracto or Hydrometer?

[SirLight1337]

I recently purchased a refractometer from Marine Depot and it says my salinity is higher then what the hydrometer says. I think i should trust the refracto but that means id have to add a good amount of RO/DI water.

Go with the refracto reading and add fresh ?

TIA

 

[Pghjeff71]

Hi, my hydrometer shows consistently lower readings than the refractometer. I am much more willing to trust the refractometer. If your LFS does water samples using a refractometer I'd also try that too.

Did you calibrate the refracto using distilled water?

- Jeff

 

[Smo]

It should either come with a test sample or do the calibration with distilled water.
You should trust the refractometer vs hydrometer. I had 2 swing arm hydrometers and both were registering .003 - .004 less than my refractometer. Needless to say I was running a 1.0295 SG. All my corals and livestock were just fine, although they do look better now with a SG of 1.026. It took me a whole month to bring it down.

Be very careful lowering your SG to where you want it. Rapid changes in salinity stress out corals, fish, and especially invertebrates.

 

[SirLight1337]

thanks for the headsup.

My hydrometer reads .022 my refracto is reading .025

 

[Pghjeff71]

Hi, these are my results from an earlier post:

1.23SG (refractometer)
1.25SG (glass hydrometer)
1.18SG (swing arm hydrometer)



(edited for clarification)

 

[seaham358]

Sirlight the refracto is the best way we can measure SG the hydroms are crap... The refracto comes calibrated but you can check it with distilled water...
You SG is good right where it is no need to lower it...

 

[zacdl]

Might wanna check this thread:
http://www.aquariumadvice.com/viewtopic.php?t=53914

 

[zacdl]

The best way to check the accuracy I think would be to take 2 differant hydrometers (if you still want to use them) and see how they measure up. If they are differant, maybe get a 3rd and see which one is the correct one.

 

[seaham358]

The best way to check the accuracy I think would be to take 2 differant hydrometers (if you still want to use them) and see how they measure up. If they are differant, maybe get a 3rd and see which one is the correct one.

What happens if there all different get a 4th then a 5th?

Refractometer is the best tool we can get for measuring SG/Salinity.

 

[SirLight1337]

cool, thanks for all the responses and info

Ill trust my refracto from now on. im glad it worked out to my advantage though.

 

[zacdl]

What are the chances 3 would be differant?????

 

[gilraen]

hyrdometers SUCK!! I tested my tank on one side and it read 1.023 (cool) then it occur to me to test on the other side of the tank and the reading was 1.018!! mind you, there were no bubbles in the thing and I've always cleaned it with RO H2O after each use. Not to mention it's only about 2 months old!! Needless to say this morning I ordered my first refractometer. 8)