Refractometer help

[mihali]

Can I use Brightwell aquatics calibration solution if it’s not 25 degrees celcius

 

[FUNGI]

You should be able to if you have a ATC refractometer

 

[mihali]

I do

 

[mihali]

The refractometer is coming in a few days and I have the fluval hydrometer is that any good for now

 

[FUNGI]

From what I understand regarding ATC:
AUTO TEMPERATURE COMPENSATION (ATC)There is a lot of misunderstanding concerning the way the ATC feature worksand its effect on the refractometer at different ambient room temperatures.Salinity is a measurement of a mass of salt in a mass of water and thereforedoes not vary with temperature however a refractometer does not measuresalinity directly but measures the refractive index which is then displayed assalinity. The refractive index of a solution does vary with temperaturetherefore the reading that you measure with a refractometer is alwaystemperature dependant.An ATC refractometer has a bimetal strip inside the instrument that movesthe reading scale as the temperature changes to compensate for the changein refractive index.What people do not generally understand is that it is the temperature of theinstrument and not the water temperature that is important as the smallsample of water used for testing will equilibrate within seconds to thetemperature of the refractometer.

 

[FUNGI]

SOURCE: https://www.theaquariumsolution.com/sites/default/files/downloads/SEAWATER REFRACTOMETER V2.pdf

Its a pretty good read.

 

[FUNGI]

The refractometer is coming in a few days and I have the fluval hydrometer is that any good for now

You'll be ok with that for a general read until the refrac arrives...

 

[Randy Holmes-Farley Verified Community Expert]

I’ve never understood and do not agree with the assertion by manufacturers that the temp matters for an ATC refractometer calibration. I think they do not understand the implication of the purely mechanical temperature compensation that acts equally well on the standard as it does in the sample.

 

[mihali]

Are you saying temp doesn’t matter

 

[exnisstech]

Randy has a recipe for diy calibration fluid using table salt. I would trust it over a comercial product. The comercial product may or may not be accurate but if it isn't accurate your won't know unless you have something to compare it to.
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

 

[Randy Holmes-Farley Verified Community Expert]

Are you saying temp doesn’t matter

Within the range of the ATC temp correction, and if it works properly, yes, it does not matter.

 

[fishkat]

Within the range of the ATC temp correction, and if it works properly, yes, it does not matter.

Will a different brand of table salt work to make your diy salinity standard?
fishkat

 

[Randy Holmes-Farley Verified Community Expert]

Will a different brand of table salt work to make your diy salinity standard?
fishkat

Yes, assuming you weigh it and it is not damp, any brand works.

 

[BriDroid]

Randy has a recipe for diy calibration fluid using table salt. I would trust it over a comercial product. The comercial product may or may not be accurate but if it isn't accurate your won't know unless you have something to compare it to.
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

Agree totally! I bought one off Amazon that was WAY off. I now make my own!

 

[rhitee93]

Agree totally! I bought one off Amazon that was WAY off. I now make my own!

Yep, happened to me too. I thought I had been running at 35ppt for 18 months only to find out the calibration standard that came with my refractometer was off and I was only at 30ppt.

 

[BriDroid]

Yep, happened to me too. I thought I had been running at 35ppt for 18 months only to find out the calibration standard that came with my refractometer was off and I was only at 30ppt.

I only figured mine out after I bought a used Ice Cap salinity pen and was like “something is off!”