Refractometer Calibration

[reefrider777]

I have some 1.026 calibration solution for my refractometer. Everytime I use the solution I need to change the calibration. Even if I calibrate back to back (it's usually not that drastic when done back to back). Is this normal and part of the ATC?

 

[twilliard]

I would have to say it's temperature related

 

[James Miller]

The instructions on mine says to use purified water and set to 1.00. (which is bottom line). I set mine first time and used for 2 weeks, checked it again with same bottle of purified water and it need no adjustment. I still check once a month to play it say and even used a different bottle of the same brand of purified water. Distilled water works just the same. Hope this helps.

 

[pugcrush]

I have some 1.026 calibration solution for my refractometer. Everytime I use the solution I need to change the calibration. Even if I calibrate back to back (it's usually not that drastic when done back to back). Is this normal and part of the ATC?

What brand is the refractometer? I use 2 to back up my readings. My first one that is 6+ yrs old is 100% trustworthy. I added a 2nd one a few yrs back that has to be calibrated quite often.

 

[James Miller]

ATC.

 

[stunreefer Verified Sponsor]

If possible, only tighten the screw when calibrating, rather than loosen. This won't work on some units, however.

What brand refrac are you using?

Regardless it's good habit to cal frequently.

The instructions on mine says to use purified water and set to 1.00. (which is bottom line). I set mine first time and used for 2 weeks, checked it again with same bottle of purified water and it need no adjustment. I still check once a month to play it say and even used a different bottle of the same brand of purified water. Distilled water works just the same.

You should cal with refrac solution, not DI. It calibrates hobby grade refracs into the range we actually care about; hobby grade refracs are not linear in measurement over a large range. More info here.

 

[James Miller]

I actually put the bottle of purified in the same room my tank is in, set it to that room temp and calibrate. Refractometer is kept in same room. I know temperature changes does change the calibration, so using cold test water then testing at room temp will throw it off

 

[reefrider777]

If possible, only tighten the screw when calibrating, rather than loosen. This won't work on some units, however.

What brand refrac are you using?

Regardless it's good habit to cal frequently.

You should cal with refrac solution, not DI. It calibrates hobby grade refracs into the range we actually care about; hobby grade refracs are not linear in measurement over a large range. More info here.

The brand of the refractometer is BioTek Marine