Reading Salinity Milwaukee MA887

[remi010]

I have a milwaukee digital salt meter. Now I calibrated him with Ro water. On s.g gives the meter 1.025 and if I press the 2nd and 3rd time still 1.025. If I measure it on ppt then give the meter 33ppt and at the 2nd and 3rd time press 34 and at the 5th time 34ppt. The seawater is 25.2 degrees and on the meter 21.7 degrees, there is an ATC function on it, do I still have to calculate this back to 25 degrees? Am a bit confused

 

[ckalupa]

You are reading a difference between 1.0249 (33ppt) and 1.0256 (34ppt).

It compensates temperature automatically.

 

[remi010]

Here are the pic's. What is the Salinity of nu reeftank. I want to run on 34 ppt

 

[remi010]

P

 

[ckalupa]

You are attempting to hold a pretty tight range. Are you washing the MA887 sample head with RO between each test?

32 ppt =1.0241
33 ppt = 1.0249
34 ppt= 1.0256
35 ppt = 1.0264

That meter only displays S.G. to three decimal places so there is rounding happening with the 4th decimal place when looking at S.G.

Items that could affect it = From the calibration instructions:

Fresh batteries
Shielding the sample stand from bright lights
Absorbing the old sample with soft tissue
Wiping the prism with a soft cloth
Sufficiently filling the sample stand
Distilled water vs DI (You mentioned calibration with RO - that may not be 0 TDS) They spec Deionized or Distilled

Just things to consider if you are trying to hold that tight

 

[Randy Holmes-Farley]

I don't really see a problem. The manufacturer claimed uncertainty of the meter is larger than the precision you are looking for.

Accuracy ±2 PSU
±2 ppt
±0.002 S.G. (20/20)
±0.3°C / ±0.5°F