Help needed with Milwaukee salinity monitor

Orm Embar · Dec 8, 2020

I have a Milwaukee salinity tester, and it used to work very well (when zeroed with the supplied distilled water, it would read the 1.025 SG sample as 1.025).

I haven't used it for a while, but now it's reading my 1.025 SG sample as 1.031 despite repeated attempts at cleaning the prism (RO/DI water left to dissolve any residual salts, and then a Q-Tip gently with 70% isopropyl alcohol then rinsed off). Still having the same issue. There is a bit of cloudiness around the edges of the visible prism, but that's been there.

I'm worried that the lens is somehow scratched/damaged and that my meter is therefore inoperable.

Any recommendations or ideas on how to get it working accurately again? I will be taking my reference standard to a LFS for crossmatching, but it's been in a selaed plastic bottle as it was shipped and I never leave it open.

DC Reefer · Dec 8, 2020

Couldnt tell from the post are you still using the supplied distilled water to calibrate and having this issue?

StlSalt · Dec 8, 2020

What does it read if you test RO/DI water?

piranhaman00 · Dec 8, 2020

Calibrate with RODI and then read RODI.

Randy Holmes-Farley · Dec 8, 2020

You can also check it with a 35 ppt seawater standard made for refractometers.

homer1475 · Dec 8, 2020

Since it hasn't been used in a while, How old is the 1.025 standard? It may have evaporated and your meter is actually reading correct.

If you can zero it out with RO/DI or the supplied distilled and it still reads 0. I would question the bottle of 1.025 fluid.

Willper · Dec 8, 2020

I had a problem with the Milwaukee electronic salinity tester and called Milwaukee. They asked me some questions and decided to replace it even though it was 2 years old. Great service.

Orm Embar · Dec 9, 2020

1) When calibrated with distilled water (supplied), it reads the 1.025 specific gravity standard as 1.031
2) I haven't tried it on a different standard; I should try this. I'm not sure why I would have evaporation in a sealed bottle, though. I try to keep it on tight, but it is more than a year old.

I'll take it in to my LFS to see how it reads there; maybe the problem is my standard and not the device . . . which would be great!

Orm Embar · Dec 9, 2020

Update: when tested at the LFS on their 1.025 salinity tanks (refractometer checked and I think salinity checked electronically as well), my Milwaukee read 1.030. I ended up buying a Hanna salinity/conductivity pen (so far, so good!) and a backup swing hydrometer. I may also buy a Tropic Marin float hydrometer as a gold standard (eventually). So . . . it is certainly possible for electronic refractometers to have issues as above. I may contact Milwaukee to see what their recommendations are.

Orm Embar · Dec 10, 2020

Latest update: my tank water tests at 36.0 ppt by Hanna (conductivity), and at the LFS the same water tests at 1.027 SG by refractometer (they calibrate theirs daily per their report). At this point, the Hanna conductivity meter seems accurate and I will be using that going forwards. I plan on correcting by 0.1 ppt per day to get back to 35.0 PPT.