Salinity Testing with MA887

[enzo86]

Not sure if this is the correct sub for this? I got my ICP test back a few days ago and was surprised to see that my Salinity was around 31.5 PSU. I have a Milwaukee MA887 and a handheld Refractometer that I quit using after the 887 came in. I Zero out the Milwaukee with RODI, also with the Calibration 1.00 solution that came with the unit, but it still reads about 2 PPT High with the 35 PPT Calibration Solution. Thinking I might have had bad or contaminated Calibration Solution I purchased more from a different provider, but I get the same results.

Are other using this same unit and are getting similar results? I ran my handheld through the same calibration process and its dead on now. Guess I should have cross-checked both units before. Thanks in advance for any input.

 

[jsker]

Question, are you covering the test sample so that light does not distort the test?

 

[dragon99]

Mine consistently reads 2ppt low. I check it against a refractometer occasionally to make sure, but it's been consistent for ~1yr that way.

 

[enzo86]

Question, are you covering the test sample so that light does not distort the test?

YES

 

[enzo86]

Interesting, looks like this error is within their posted tolerance (barely)

 

[120reefkeeper]

I’ve seen this before and it’s most likely the 35ppt solution.

Correct me if I’m wrong , but I believe the only calibration they require is the steam RODI water. I don’t believe anywhere does it say to use the 35ppt solution.

I’d also like to note that I have the same unit. I have cross checked it against a 35ppt solution and mine also reads a little off.

I prefer to read it on the SG scale.

I’ve used my unit for about a year and a half and I only calibrate with the steam RODI unit as instructed.

I’ve had zero issues and it’s been rock solid keeping my salinity at 1.025

Hope this helps! [emoji4]

 

[Giddyup]

What is "steam" RODI ?

 

[reefwiser]

When I use mine and wash the dish area well with RO/DI water to clean it off. You can get so residue from the last test you did if you do not clean it off and wipe dry before doing the zero test. I do the zero test every time I use it. I also use my refractometer every so often and I also use a Tropic Marin Hydrometer. Always good to have several ways to test a critical parameter.

 

[BCSreef]

What is "steam" RODI ?

I think it means distilled water.

My Milwaukee reads SG about 0.002 high. However, it’s been extremely consistent for over three years.

 

[120reefkeeper]

What is "steam" RODI ?

It is the supposed special water used to calibrate this unit. It comes with the unit as a kit.

It’s steam distilled water.

 

[enzo86]

I’ve seen this before and it’s most likely the 35ppt solution.

Correct me if I’m wrong, but I believe the only calibration they require is the steam RODI water. [emoji4]

I have used both the provided Calibration RODI, and my own RODI, both provide the same error, Both fall on 0 or 1.00 before calibrated (Zero Button), I have also tested against their provided 1.025 test solution and it comes out at 1.027 (within their margin of error) Think my unit is just off and as long as it remains off by the same amount every time we won't have an issue, I can cross-check it against my other refractometer. Looks like my unit gets the label maker with a warning that it reads +2 High.

 

[Randy Holmes-Farley Verified Community Expert]

I’ve seen this before and it’s most likely the 35ppt solution.

Correct me if I’m wrong , but I believe the only calibration they require is the steam RODI water. I don’t believe anywhere does it say to use the 35ppt solution.

I’d also like to note that I have the same unit. I have cross checked it against a 35ppt solution and mine also reads a little off.

I prefer to read it on the SG scale.

I’ve used my unit for about a year and a half and I only calibrate with the steam RODI unit as instructed.

I’ve had zero issues and it’s been rock solid keeping my salinity at 1.025

Hope this helps! [emoji4]

It does not say to use it, but is not wrong to check it with a suitable 35 ppt solution.

 

[DaddyO NJ]

I have the same problem -- MA887 is consistently reading 1.028. I zeroed with RODI and the zero solution it came with. Also, tested with two separate 35ppt solutions with the same result. I honestly never realized it was so far off and am embarrassed to say how long I have been using it. Thought that electronic reading would be perfect or at least better than trying to read the regular refractometer. Let's hear it for the Luddites!

 

[User1]

I know this is a tad old and I'm necroing an old thread but was going through the calibration of my MA887 using distilled, reading 0, setting calibration, then using a 35 ppt solution only to read 1.028 Repeatedly. Take a sample of my aquarium and it reads 1.028. Was going to check via the hand held plastic devices but alas my GSD thought it was a chew toy (my fault for leaving it on the floor although I'm thinking it must have tasted off to her, the goof). Anyway wonder what side of the +- I'm on...

Apex is measuring 34.5 so maybe I'm actually at 1.026 S.G...

 

[smartwater101]

Apex is measuring 34.5 so maybe I'm actually at 1.026 S.G...

I would never trust the Apex probe. I use the Hanna Digital Refractometer and a second handheld Refractometer just to confirm the accuracy now and then. The Apex probe seems to shift and never stay consistent.

 

[User1]

I would never trust the Apex probe. I use the Hanna Digital Refractometer and a second handheld Refractometer just to confirm the accuracy now and then. The Apex probe seems to shift and never stay consistent.

Yeah, I agree. I only use it as a reference. In this case after I calibrated the MA887 then ran through the measurements I looked to see what the Apex was reading. Hard to tell which side I'm on with regards to the Milwaukee margin of error without another way to check is all. I'll have to go pick up another plastic hand held hydrometer and not let it within my dogs reach

But yes - agreed with regards to the Apex. How do you like the Hanna out of curiosity?

 

[smartwater101]

But yes - agreed with regards to the Apex. How do you like the Hanna out of curiosity?

I love it. I've probably had it for 10 years at this point and its always been great. Expensive (I think it was like 300+ at the time... probably around 250 nowadays) I use it weekly and the battery still shows 97% lol

 

[hotashes]

It’s best calibrating salinity checkers with fluid at 35ppt as that’s the end of the scale being tested. When using rodi at 0 you are widening the accuracy to the furthest point. Resulting in mixed readings.
I’ve learnt it’s always best calibrating any salinity tester with 35ppt calibration fluid

A.

 

[infinite0180]

I use a hanna refractometer at work to test %Brix but it is literally the same device with dofferent programming. Sometimes i need to “cup” my hand over the sample when i press the read button to block out some light from the room. It tends to read better that way. Worth a shot...

 

[reefwiser]

One thing I have learned when using the MA887 or any digital refactor is to clean off the optical sensor well with RO water before doing any thing with the device.
I take a pipette and wash the sensor 10 times with RO water. Removes any residue on the sensor.