Refractometer

[shwareefer]

My thoughts were definitely based on my own assumptions - optics mounted to metal, metal expands or contracts, optics move with it, reading becomes inaccurate.

 

[Randy Holmes-Farley]

My thoughts were definitely based on my own assumptions - optics mounted to metal, metal expands or contracts, optics move with it, reading becomes inaccurate.

That may be part of the problem, but that is not the explanation given by refractometer manufacturers of why ATC is needed:

Automatic Temperature Compensation (ATC)

Automatic Temperature Compensation (ATC), Refractometers common information, definitions, Encyclopedia, Refractometer, Pocket refractometer, Handheld refractometer, Palm refractometer, Measuring of the refractive index

www.refractometer.eu

 

[shwareefer]

That link is in my favourites, so obviously I read it and saved it once before.

Not to be devil's advocate but considering that we're peering through a sliver of water, it seems to me the water temperature would quickly become the temperature the refractometer is, and as long as the device was consistently the same temperature, the sliver of water and it's temp would become a non factor. Not arguing, just thinking.

 

[Randy Holmes-Farley]

That link is in my favourites, so obviously I read it and saved it once before.

Not to be devil's advocate but considering that we're peering through a sliver of water, it seems to me the water temperature would quickly become the temperature the refractometer is, and as long as the device was consistently the same temperature, the sliver of water and it's temp would become a non factor. Not arguing, just thinking.

Yes, that is true. It all rapidly comes to room temp (or the temp of the refractometer since its mass is very high relative to the water).

But room temps vary, hence the need for the ATC. The effect on reported salinity is substantial even from a few degrees difference.

 

[BeachBumTX]

The tropic marin precision glass hydrometer is $31 and blows everything else away. Far more accurate and precise. Don’t scoff at the idea of using a hydrometer... this one is very different than the old plastic swing arm pieces of junk.

I actually like glass hydrometers and was disappointed when the local LFS didn't have it.

 

[polyppal]

Hello,

My LFS has a refractometer for $70. I see on Amazon that there are some for $20. Should I be leery about the cheaper price tag? Could they be junky? Thoughts?

FISH ON!!,

BUM

I will likely upgrade to the Hanna, but I have the cheap amazon one and it works fine