Refractometer issues

[raythereefer]

When testing My salinity the first reading will usually be high , followed by the reading dropping slightly every time . Has anyone else had this issue or is my refractometer ready for the bin ? Have calibrated it to 0 using R.O but it always does this. First test can be as high as 1.032 and generally gets to the stage where it will settle between 1.025 - 1.027 for half a dozen tests in a row but just makes me uneasy that I'm getting different readings. But always starting high and gets gradually lower ?

 

[crazyfishmom]

When testing My salinity the first reading will usually be high , followed by the reading dropping slightly every time . Has anyone else had this issue or is my refractometer ready for the bin ? Have calibrated it to 0 using R.O but it always does this. First test can be as high as 1.032 and generally gets to the stage where it will settle between 1.025 - 1.027 for half a dozen tests in a row but just makes me uneasy that I'm getting different readings. But always starting high and gets gradually lower ?

Calibrating with RODI may not be the best way to go. As far as I understand, it is recommended that you purchase a calibration solution at 35 ppt and use that instead of RODI.

 

[raythereefer]

Calibrating with RODI may not be the best way to go. As far as I understand, it is recommended that you purchase a calibration solution at 35 ppt and use that instead of RODI.

I understand that but even still it doesn't explain why my test results are slowly dropping from 1 minute to the next ?

 

[Randy Holmes-Farley Verified Community Expert]

When testing My salinity the first reading will usually be high , followed by the reading dropping slightly every time . Has anyone else had this issue or is my refractometer ready for the bin ? Have calibrated it to 0 using R.O but it always does this. First test can be as high as 1.032 and generally gets to the stage where it will settle between 1.025 - 1.027 for half a dozen tests in a row but just makes me uneasy that I'm getting different readings. But always starting high and gets gradually lower ?

What refractometer?

Sounds like it may be a temperature equilibration issue. I’d suggest taking a water sample, let it sit next to the refractometer for a while (an hour maybe) then try it and see if the same thing happens.

 

[redfishbluefish]

Agree with using a calibration solution....but that doesn't address the drifting numbers.

How old is the refractometer? And does the little swinging cover plate swing freely?

Might wish to check out this post:

Lubricate Your Refractometer

 

[raythereefer]

What refractometer?

Sounds like it may be a temperature equilibration issue. I’d suggest taking a water sample, let it sit next to the refractometer for a while (an hour maybe) then try it and see if the same thing happens.

Quite an old one judging by the box ! Will give that a go thanks randy I suppose temperature equilibration could make sense as the more tests I do i suppose the closer the temperature matches and generally more settled the results become. Maybe time to grab a new one to be sure regardless

 

[raythereefer]

Agree with using a calibration solution....but that doesn't address the drifting numbers.

How old is the refractometer? And does the little swinging cover plate swing freely?

Might wish to check out this post:

Lubricate Your Refractometer

Probably older than me by the looks of it that is swinging fine so that's one more thing to rule out but thanks for the insight

 

[Stang67]

I really like the fauna marin hydrometer.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

 

[raythereefer]

I really like the fauna marin hydrometer.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

Looks good , May look in to that as I run my tank between 77 -78 so no need for the conversion chart