national calibrate your refractometer day!

[Jim_Dont_Care]

i use fluid but also if i check it with ro\di it comes up zero is all i was saying so its acurate for me

[woods4542000]

Originally Posted by TG_Lansing

OK, I am also paranoid about my refractometer calibration. I normally use RO/DI as my calibration solution came with ran out. Where can I get a calibration fluid? Any cheap but good places?

You can get it at preuss for like 7$ I think.

[mf2055]

Originally Posted by katymunoz

Ok so now I am truly confused with my calibration!

So I have two solutions and one solution says its 35 ppt and 1.033 refractive index, and the other one says it is 35ppt and 1.026 refractive index...... So how is this possible?? If I calibrate one to 35ppt then the other is off when I put it on my refractometer.... So I officially don't know what my salinity is!

Salinity is temperature dependant.

[katymunoz]

Originally Posted by mf2055

Salinity is temperature dependant.

Both say at 77 degrees right on the bottle. The one says:

53 ms solution. 35ppt, 1.033 refractive index at 77 degrees.


The other bottle says 35ppt, refractive index 1.026 at 77 degrees.

So that's where my question still is, how can two different solutions at 35ppt have different refractive indexes according to the manufacturer.

[dputt88]

Originally Posted by mf2055

Salinity is temperature dependant.

salinity is not temperature dependent, specific gravity is.

assuming your solution is completely dissolved and it reads 35 parts per thousand, no matter how the temp swings (as long as it doesn't boil) you will always have 35 parts per thousand, unless you found a way to create matter.

specific gravity is temperature dependent because it refers to the density of a solution, not the concentration. as we know at different temp a solution will have a different density (ice floats in water).

[dputt88]

Originally Posted by katymunoz

Both say at 77 degrees right on the bottle. The one says:

53 ms solution. 35ppt, 1.033 refractive index at 77 degrees.


The other bottle says 35ppt, refractive index 1.026 at 77 degrees.

So that's where my question still is, how can two different solutions at 35ppt have different refractive indexes according to the manufacturer.

IMO, the way you can have 2 salinity matched solutions with different SG at the same temp is because salinity only refers to the concentration of salt in the solution, all the other ingredients to the solution may vary between brands, therefore so does the solution density.

[dputt88]

wow, just realized you were talk refractive index and i was still in SG mode. anyways here a article on refractometers maybe your answer is in there. i tried reading all of it but unfortunately i have to leave the computer now

Refractometers and Salinity Measurement by Randy Holmes-Farley - Reefkeeping.com

also where are you getting those numbers? why are their refractive indices so low? are you sure they aren't 1.33 and the other 1.27.

if so i would use the calibration fluid with 1.33 refractive index because that's the same RI that you'd expect from your tank water.

this is why i use a hydrometer, its a lot easier to understand. lol.

[katymunoz]

Lol yes 1.33 and 1.26 sorry

[doogle]

Temp affected specific gravity is a good reason not to use hydrometers. Especially the old ones that are not "temp adjusted". But still.