Calibration solution wrong?
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Randy Holmes-Farley
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A sg of 1.028 for a reef tank is not a big problem, but I'd slowly lower it if real.
That said, I can't know if the new refractometer is off or if the fluid is off. You can make your own if you have a scale.
That said, I can't know if the new refractometer is off or if the fluid is off. You can make your own if you have a scale.
Travis Stewart
Valuable Member
Each refractometer has a certain suggestion on which calibration “fluid” to use. Red Sea suggest RO water. When I use this same exact fluid, mine is off also. Try comparing it with RO or look up what is suggested with this specific tool.
chipmunkofdoom2
Always Making Something
This is why I have never been a fan of the Milwaukee digital refractometer. Calibrating a device designed to read samples at S=35 with freshwater leaves a lot of room for error.
I would make a DIY standard as recommended by Randy. I followed Randy's recipe and the Aqua Craft solution matched the DIY solution exactly. What's more, I was able to verify both the DIY solution and the Aqua Craft with a third salinity standard from American Marine. All three solutions matched exactly, with almost no variation whatsoever. I would be curious to see what your results are. Given the potential for miscalibration, I'm inclined to believe the Aqua Craft solution is correct and the digital refractometer is wrong, but the only way to know that is to test with another standard.
It's worth noting that calibrating with freshwater is likely "good enough" and will probably produce consistent results. I just personally hate to settle for "good enough" when I can put in a little extra effort and know for sure that the results are accurate.
I would make a DIY standard as recommended by Randy. I followed Randy's recipe and the Aqua Craft solution matched the DIY solution exactly. What's more, I was able to verify both the DIY solution and the Aqua Craft with a third salinity standard from American Marine. All three solutions matched exactly, with almost no variation whatsoever. I would be curious to see what your results are. Given the potential for miscalibration, I'm inclined to believe the Aqua Craft solution is correct and the digital refractometer is wrong, but the only way to know that is to test with another standard.
It's worth noting that calibrating with freshwater is likely "good enough" and will probably produce consistent results. I just personally hate to settle for "good enough" when I can put in a little extra effort and know for sure that the results are accurate.
CircleCityBill
Community Member
My Milwaukee refractomer gives the same value with that calibration fluid.
dazoc
Community Member
Mine gives 1.028 or 1.029. with using aqua craft also. So with the solution being a calibrated 35 ppt. Do I run my tank at 1.028-1.029 and assuming it is gauge error? If the gauge is testing solution at 35 ppt as 1.028, my reef water on the gauge reads 1.028, that should be an actual 35ppt. And keep my salinity to match the error in gauging?
Randy Holmes-Farley
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I can't be sure which is wrong. A second standard would help answer the question.
So, I just purchased a digital refractometer because my handheld had years of pretty good use, so I thought. My handheld measures my salinity at 1.025 my new digital reads at 1.028. I tested the calibration solution and it also reads at 1.028? My sps seems really dull, so my question is should I lower my salinity comparable with my digital readings? Is 1.028 to high?
The Aqua Craft calibration fluid is 35ppt which is 1.028 not 1.025, the meter is making the correct reading. The fluid that comes with the Milwaukee is 1.025. I had the exact same thing happen to me when I bought this unit and thought it was off but it was me that wasn't thinking straight!
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NY_Caveman
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You could also take the Milwaukee to your LFS and ask them to test it with their water which I assume they know or can test with their equipment. Just need a known source.
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jason7570
IG Riot_Corals
Their customer service is really good, I’m sure I just received a defective one. My new one I’ve had for about 2 months, still in the box and never used. Can’t beat the handheld ones in my opinion..
CMO
Valuable Member
I'm experiencing the same thing now between my BRS ATC and Milwaukee. Coupling with ICP test which show my sodium is low I'm inclined to believe that the Milwaukee is overstating salinity by about 0.002 (which is within range of the expected error). Salinity with Milwaukee reads 1.025 while my ATC reads 1.023. I have the specific calibration solution for each devise and just calibrated them before these tests.
Travis Stewart
Valuable Member
Ahhh this make sense! I thought it was supposed to be 1.025 also. Great to know! Thank you!
Dawsokj1988
Active Member
I'm convinced with the Milwaukee 1.028 = 1.026. I've tested 3 different calibration fluids and compared my GHL conductivity probe with the ICP test from ATI. I think it's having to calibrate it with rodi water that throws it off. I just use 1.028 as my reference point now.
CMO
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