PINPOINT Salinity Calibration Fluid

[jstlsn]

Can PINPOINT Salinity Calibration Fluid go bad? I have a bottle that I purchased out at BRK on 02/10/2007. I just calibrated my refractometer and it was off by .004. It has been a few months since I last calibrated it, but I don't understand how it could get so far off. If the calibration fluid is correct the salinity in my tank is too high. Any help would be greatly appreciated.

 

Thanks

Brad

[Jon Lazar]

Brad,

 

I'm assuming you've tried multiple times and keep getting the same results? Have you doublechecked with a second benchmark, like RO/DI water with a salinity of 0 ppt?

 

I've gotten incorrect readings with my refractometer through poor lab practices like not cleaning the equipment properly after a reading. This resulted in remnants from the first sample skewing the result of the second. Make sure you clean the prism glass and both sides of the plastic coverplate. If you wait a long time while taking a reading, the water may begin to evaporate from under the coverplate causing salinity to rise.

 

Jon

 

Can PINPOINT Salinity Calibration Fluid go bad? I have a bottle that I purchased out at BRK on 02/10/2007. I just calibrated my refractometer and it was off by .004. It has been a few months since I last calibrated it, but I don't understand how it could get so far off. If the calibration fluid is correct the salinity in my tank is too high. Any help would be greatly appreciated.

 

Thanks

Brad

[tbittner]

Float the fluid in the tank so the temperature equalizes before calibrating the refractometer. Temp can cause that much of a flucuation.

[jstlsn]

Jon

 

Thanks for the help. I have tried RO/DI and it is 1.000 ( 0 ppt). I have also tested the calibration fluid about 25 times and my tank water about 25. And I have cleaned the prism glass and plastic cover between each. When I adjust the refractometer for the calibration fluid to read 1.026 (approx. 35 ppt), my tank water is testing at 1.031. That seems extremely high to me. However, everything in my tank seems happy. The fish are swimming around and eating. Coral all have their polyps out. RBTA looks happy. That is why I am wondering if the calibration fluid is off. I would think that 1.031 would have an adverse affect on my inhabitants.

 

tbittner, I have also tried floating the calibration fluid in the tank. The reading was slightly different than before I floated it. But still doesn't explain the differences.

 

Thanks

Brad

 

 

Brad,

 

I'm assuming you've tried multiple times and keep getting the same results? Have you doublechecked with a second benchmark, like RO/DI water with a salinity of 0 ppt?

 

I've gotten incorrect readings with my refractometer through poor lab practices like not cleaning the equipment properly after a reading. This resulted in remnants from the first sample skewing the result of the second. Make sure you clean the prism glass and both sides of the plastic coverplate. If you wait a long time while taking a reading, the water may begin to evaporate from under the coverplate causing salinity to rise.

 

Jon

[jnguyen4007]

Jon

 

Thanks for the help. I have tried RO/DI and it is 1.000 ( 0 ppt). I have also tested the calibration fluid about 25 times and my tank water about 25. And I have cleaned the prism glass and plastic cover between each. When I adjust the refractometer for the calibration fluid to read 1.026 (approx. 35 ppt), my tank water is testing at 1.031. That seems extremely high to me. However, everything in my tank seems happy. The fish are swimming around and eating. Coral all have their polyps out. RBTA looks happy. That is why I am wondering if the calibration fluid is off. I would think that 1.031 would have an adverse affect on my inhabitants.

 

tbittner, I have also tried floating the calibration fluid in the tank. The reading was slightly different than before I floated it. But still doesn't explain the differences.

 

Thanks

Brad

 

 

Brad,

 

What this sounds like is that somewhere along the way, you might have added more salt water so over time, the salinity level in the tank rises.

 

If you need to have your refractometer calibrated, I have calibration fluid so I can help you calibrate it.

[lancer99]

Brad,

I don't think the calibration fluid can go bad, so that's pretty weird.

 

Just wanted to mention that before I got a refractometer, I was using one of those swing-arm type hydrometers, and was running my tanks at 1.029, with seemingly no adverse effects. So maybe 1.031 isn't high enough to cause any problems either....?

 

-R