Help with refractometer salinity and temperature

LocalPref

New member
Okay I am about to pull my hair out trying to understand Salinity and the effect temperature has on it. Here is my situation. Ideally I would like to run my reef tank between 34 and 35 ppt I keep the temperature of the tank between 78 and 78.5. My room temperature is around 70 degrees.

Now onto my refractometer it is made by red sea. The instructions for calibration say I need to calibrate it using RO water when room temperature is between 71.6 and 77(converted Celsius to Fahrenheit).

I have some calibration fluid and ro di water and if I calibrate using either they back each other up both are left sitting in the same room as the refractometer so I would guess they are around room temperature. Unfortunately the refractometer doesn't seem to hold the calibration and is off by about three points the next day so I need to calibrate every day I plan to use. I got another one same brand and it does the same thing.

So now onto measuring my water. I have made up a batch 100 gallons of water it is heated up to my around my tanks temperature 78.5.

Now I understand temperature and salinity are bound not sure the math behind it but that a change in temperature will change salinity reading. So how to I compensate for the difference of temperature of what I calibrate at which is slightly outside of spec and test at versus the temperature I keep my tank at? Also when I test do I need to pull a sample from the tank and allow it get to room temperature? It says it does automatic temperature compensation and to use it in temps between 15-35 Celsius. So I think I'm okay to just put a few drops on the refractometer and let it sit for a minute and take the reading. My biggest concern is that I have to calibrate it daily and the room temperature is below the low point for calibration so I am not getting correct readings.
 
1... always use calibration fluid not ro/di water (assuming the fluid is accurate)
2..... the temperature of the refractometer can change the calibration. So, if you calibrate one day at 68 degrees and pick it up to use the next day at a temperature of 75 degrees, the calibration will likely be off. Always calibrate right before every use.

3....the light you are viewing it in can make a big difference, once calibrated use the same light source for testing.

the temperature of the water being tested doesn't make a difference because the 3 drops you put on the refractometer will quickly become the temperature of the refractometer......so room temperature is what you're concerned about .....
 
Get a vital sine refractometer. Temperature compensation actually works and the calibration is rock solid. I have been using mine for years and have never had to adjust it after the initial calibration.
 
help

help

I have a problem I just got new pinpoint calibration
fluid I am way off buy .004. to high
The old fluid and r/o water check ok.1.026
Do I trust the new fluid?
helppppppppppppppppppp
 
Yes. It is useless to calibrate with RODI. I would trust the new solution over any bottle of solution that has been opened.
 
Back
Top