Refractometer/Hydrometer/GHL

[airdrie5]

I just tried the calibration fluids that came with the GHL and the Pinpoint and this is what my refractometer measured.

GHL 50mS @ 25 degrees: 1.018

Pinpoint 53.0mS @ 25 degrees: 1.028

Makes no sense to me. Perhaps the calibration fluids are contaminated or old?

Contamination seems unlikely as both of the bottles have never been left open and are under 30 days old from both manufacturers (store purchased).

[rayjay]

First of all, if the Sybon refractometer is a standard salinity refractometer then calibrating it with water will result in error at standard salt water aquaria salinity.
Even if you have one of the few sea water refractometers, it's still recommended to use calibration fluid to set it.
http://reefkeeping.com/issues/2006-12/rhf/index.php

[gregzz4]

Firstly, I wouldn't worry about the hydrometer reading as they cannot always be trusted ( put it in a drawer and forget about it )
As for calibrating the refractometer;
Mine requires me to have the solution @ 68f. I take a digital thermometer with me and wander around my basement until I find that room temperature. Then I put a drop on the lens and wait a couple minutes for it to equalize before I close the cover. I've never had an issue with it when I do this.

[sphelps]

Originally Posted by airdrie5

I just tried the calibration fluids that came with the GHL and the Pinpoint and this is what my refractometer measured.

GHL 50mS @ 25 degrees: 1.018

Pinpoint 53.0mS @ 25 degrees: 1.028

Makes no sense to me. Perhaps the calibration fluids are contaminated or old?

Contamination seems unlikely as both of the bottles have never been left open and are under 30 days old from both manufacturers (store purchased).

Makes sense to me, like I said the GHL offset needs to be set. Throw out the hydrometer reading and things make more sense. The refractometer reads 1.025 while the pin point reads 1.026. I would sway towards the refractometer being more accurate than the pin point but the fact these are very close is a good sign. So you can assume the refractometer is accurate so set the GHL offset to match.

[TimT]

Refractometers should be calibrated with a seawater calibration fluid.
Swing Arm Type Hydrometers are only good for hockey pucks
Pinpoint Meters... no comment but I gave up using them a long time ago.
Floating hydrometers I don't use either.

Make sure the GHL Cond probe is cleaned and swish it through the calibration solution to get rid of any air bubbles.

Cheers,
Tim

[waynemah]

This sounds normal.

I ran through the same *problem* with mine, but when it comes down to it the refract and everything else was wrong. My profilux was right

It all came together when I aquired some NSW calibration fluid, my refract was WAY off but read properly in the profilux.

I now adjust my refract to this fluid and it's spot on with my profilux every time.