What's the deal with calibration fluid?

I got a new refractometer yesterday. I calibrated it, along with the old one to 1.026, as instructed by my LFS. I tested me reef water with both units. They read that my water was 1.020, which I found hard to believe, considering my corals looked fairly happy. I then re calibrated them with distilled water, to 0. Tested my tank again and the SG read 1.025.

So, what's the most trust worthy fluid? Calibration fluid or distilled water?

 

Calibration solution.Doesn't it say right on the bottle what its specific gravity is??What brand is it??Also keep in mind that the light used to aquire the results should always be from the same source as it can change the results.i.e. if you used sunlight to calibrate it then sunlight should be used to read your tank water.

 

IMO- the calibration fluid is closest to the area on the scale that you want accuracy.

Case in point-
My refrac. reads ~ - .02 with my RO/DI (0TDS) water
so I felt it was off by a bit and now use calibration fluid- which is at the scale closest to where yo0u want it to be accurate.

 

You're trying to do a single point calibration. By definition, the curve will therefore be inaccurate elsewhere, so why not calibrate at/near the point you actually care about?

 

I just got a new Salinity probe and calibration fluid. With it, you calibrate two points. 0.0 with the air and 35ppt with the solution at temperature. I pull my temp sensor and the probe and let them stabilize in the air. I have the calib fluid in the tank water for 30 minutes prior to get it to tank temp. then I put the Temp sensor in the sump and the probe in the fluid. wiat 20 mins to ensure it is stable and then calibrate it. I then use this same solution at the tank water temp to calibrate my Refractometer. I think I did pretty good last time with the Refracto because my water was a perfect 34.7.

 

Your corals probably are looking good due to stability. Keep that in mind when you go to adjust salinity.

 

Thank you all for your replies. I'll definitely try your ways. I'd really like to know my SG. Funny, today at 4, my clownfish spawned and they're keeping the eggs this time.