Need opinion on calibrating refractometer

[_DZ_r€€f]

Hi all... I need opinion about calibrating refractometer... I have pure water calibrating solution and 35 ppm calibrating solution and on eather im getting deferent readings. After calibrating with pur water solution to zero and then checking with 35 ppm im getting 2 ppm deference... Which should i belive. It is very importent for hypo.. I calibrated with ultrapure water to 0 and then i used other solution to check it it should read 35 but it reads 37 ppm so now i dont know which one is acurate. I attached picture of solution i using thatway u have better idea what it is.

 

[redfishbluefish]

Use the calibration solution. Also make sure the little door swings freely. If it doesn't seat all the way, you'll get wrong readings. If need be, use a toothpick dipped in WD40 to lubricate the hinge points on the refractometer, and then swing the door back and forth to free up the hinges.

 

[Rob.D]

How quickly are you reading after apply the solution? I've found that allowing the refractometer sit for 45 sec - 1 minute allows it to temp adjust.

 

[dragon99]

For measuring hyposalinity, you are better off calibrating to RO/DI water
For measuring normal salinity, you are better off calibrating to 35ppt.

It sounds like your refractometer has a slope mis-calibration which means you can't calibrate at a single point and expect correct readings at any salinity.
http://reefkeeping.com/issues/2006-12/rhf/

 

[cmcoker]

For measuring hyposalinity, you are better off calibrating to RO/DI water
For measuring normal salinity, you are better off calibrating to 35ppt.

It sounds like your refractometer has a slope mis-calibration which means you can't calibrate at a single point and expect correct readings at any salinity.
http://reefkeeping.com/issues/2006-12/rhf/

This^^

 

[_DZ_r€€f]

How quickly are you reading after apply the solution? I've found that allowing the refractometer sit for 45 sec - 1 minute allows it to temp adjust.

I waited about a min... Acording to direction on the bottle

 

[_DZ_r€€f]

For measuring hyposalinity, you are better off calibrating to RO/DI water
For measuring normal salinity, you are better off calibrating to 35ppt.

Ill try that and see what im gonna get.