Milwaukee refractometer question

[KC2020]

You're making this far more complicated than it needs to be.

Turn it on. Cover the glass with deionized or distilled water. Hit Zero. Wipe it off, cover the glass with tank water and take a reading.

I've used the Milwaukee for years and it's quite consistent and accurate within the manufacturers specs.

The manual is here.

 

[reef tank 2.0]

Says everyone!!! I make everything more difficult than it needs to be

Anyways, I get the instructions, easy peazy......my issue revolved around the green bottle says it should read 1.025, but in reality it reads at 1.028. That questions everything. I couldn't pass the green validation test

 

[Lavey29]

Says everyone!!! I make everything more difficult than it needs to be

Anyways, I get the instructions, easy peazy......my issue revolved around the green bottle says it should read 1.025, but in reality it reads at 1.028. That questions everything. I couldn't pass the green validation test

Get some distilled water or RODI and zero it.

 

[VintageReefer]

I’ll test mine now using same methods
Also

 

[esquare]

You're making this far more complicated than it needs to be.

Turn it on. Cover the glass with deionized or distilled water. Hit Zero. Wipe it off, cover the glass with tank water and take a reading.

I've used the Milwaukee for years and it's quite consistent and accurate within the manufacturers specs.

The manual is here.

Am I correctly reading that, it has a resolution of 1 so if it reads 35 it could be anywhere from 34.5 to 35.4ppt?

 

[Patx]

Says everyone!!! I make everything more difficult than it needs to be

Anyways, I get the instructions, easy peazy......my issue revolved around the green bottle says it should read 1.025, but in reality it reads at 1.028. That questions everything. I couldn't pass the green validation test

I had the same problem, frustrating a bit.
i buy some calibration fluid and do the DIY too.
nothing conclusive the MA887 always read higher.

I bought the " TROPIC MARIN High Precision Hydrometer"

I made a batch of new saltwater mix at 1.026sg / 25C⁰ (TM HYDRO)
then cheated my ro/di solution to calibrate the MA887 so that it reads 1.026sg.
since then everything has been good.
I monitor from time to time with the TM. and it's always perfect.
When the MA887 change/read 1.026 and 1.025... it's because my salt water is in reality 1.0255 !
So once set-up it's great.

Ps: I rinse it thoroughly using a syringe filled with the water to be tested before taking the reading.

for me the "STANDARD" is the TM high precision hydrometer...
no need to buy or DIY calibration fluid.
I like my MA887 once properly calibrated.

 

[VintageReefer]

Ok so I’ve read about this and am Experiencing it.

First reading not accurate on ma887?


I zeroed with deionized water and even used a brand new pipette


I then cleaned lens and tested my tank


Perfect 1.026 as expected.

I tried my calibration solution next it is 75% empty and several years old. If read 1.45 instead of 1.025. Ok. Garbage that.

I then used my deionized water and calibrated my manual refractomerer so it reads zero

I tested my tank and got what appears to be 1.028

 

[VintageReefer]

Took brand new sample from tank. Cleaned lens. Tested the milwaukee and it says 1.026
Waited 30-45 seconds. Hit read. 1.027
It now reads 1.027 every time for this sample

 

[Patx]

Took brand new sample from tank. Cleaned lens. Tested the milwaukee and it says 1.026
Waited 30-45 seconds. Hit read. 1.027
It now reads 1.027 every time for this sample

In that case here.. that's mean 1.0268

 

[EricR]

Am I correctly reading that, it has a resolution of 1 so if it reads 35 it could be anywhere from 34.5 to 35.4ppt?

Totally on-board with your question -- personally, I don't understand the popularity of refractometers at all, even "nice" digital ones like the Milwaukee,,, but that's obviously just me.

For me -- TM precision hydrometer w/500 mL cylinder for consistency (and trustability) ... and Hanna digital for x.1 ppt "resolution" for quick check when mixing salt.

*not claiming better "accuracy" but at least for some consistency

 

[esquare]

Totally on-board with your question -- personally, I don't understand the popularity of refractometers at all, even "nice" digital ones like the Milwaukee,,, but that's obviously just me.

For me -- TM precision hydrometer w/500 mL cylinder for "trustability" ... and Hanna digital for x.1 ppt "resolution" for quick check when mixing salt.

*not claiming better "accuracy" but at least for some consistency

I'm with you on the TM precision hydrometer w/500 mL cylinder

 

[OrionN]

You fish and coral could not careless that the salinity is 32 ppt or 37 ppt. Consistency and reasonable accurate is what you need. I don't get why reefers spend a ton of money for such a useless piece of equipment. Then money to get calibration solution that is inaccurate.
I got my hand-held refractometer for the last 35 years. It was 60.00 when I bought it years ago. That is a huge upgrade from the IO swing arm hydrometer or these cheap float hydrometers.

 

[EricR]

You fish and coral could not careless that the salinity is 32 ppt or 37 ppt. Consistency and reasonable accurate is what you need.

I agree completely.

I got my hand-held refractometer for the last 35 years. It was 60.00 when I bought it years ago. That is a huge upgrade from the IO swing arm hydrometer or these cheap float hydrometers.

If 60.00 means $60 USD (and implies that's cheaper than what some are mentioning), I can buy 2x Tropic Marin (allegedly "precision") hydrometers for not much more. (maybe same during "sales").

P.S. I kinda like the IO swing arm hydro -- the couple old ones I have are pretty dang close to what I accept as "my" best devices.

 

[OrionN]

I agree completely.

If 60.00 means $60 USD (and implies that's cheaper than what some are mentioning), I can buy 2x Tropic Marin (allegedly "precision") hydrometers for not much more. (maybe same during "sales").

P.S. I kinda like the IO swing arm hydro -- the couple old ones I have are pretty dang close to what I accept as "my" best devices.

Hand-held hydrometer was a lot more expensive back then when it was first adopted for reefer's use. 60.00 with inflation would be a bit more than 125.00 in today money. Still, it was a lot better than the IO arm swing or dingy hydrometer that prone to break, and a lot longer to take a reading. I don't know how this day, handheld refractometer is build. Hopefully without abuse, it should last for years.

 

[KC2020]

Am I correctly reading that, it has a resolution of 1 so if it reads 35 it could be anywhere from 34.5 to 35.4ppt?

No you're not reading it correctly. It has a resolution of 1 in PSU and ppt. It does not give readings in increments between. It has an accuracy of plus 2 or minus 2 in PSU and ppt. So it can read 2 points in either direction and be within factory specs. That's the manufacturer protecting itself from those who don't understand how to use it correctly.

I use natural seawater in my reef tank. It's collected 50 feet from the surface, one half mile from shore. My Milwaukee reads 1.025 SG after I've calibrated it with distilled water. If I calibrate mine and then place a sample on it I let the water sit on the glass for about 1 minute to warm up. Ocean temp here today was 53.2F. If I took a reading at that temp it would be wrong. If the sun is shining I put my back to the sun and hold my hand over the sample.

You can calibrate once a day. It holds the calibration when turned off. You should rinse the lens with RODI or distilled water between each test. Water should be removed with a soft tissue, we use KimWipes in the lab and at sea. A Kleenex type tissue will work, a cotton towel can scratch the lens if it's not clean.

Took brand new sample from tank. Cleaned lens. Tested the milwaukee and it says 1.026
Waited 30-45 seconds. Hit read. 1.027
It now reads 1.027 every time for this sample

Because the temperature of your tank water was higher than ambient and the internal temperature of the Milwaukee. If you read the manual you'll see it says to wait about a minute after placing a sample on the refractometer to allow thermal equilibration.

 

[gbroadbridge]

Am I correctly reading that, it has a resolution of 1 so if it reads 35 it could be anywhere from 34.5 to 35.4ppt?

No, throw away the test solution that came with it, it may be years old.

Calibrate using RODI.

If your tank reads 1.026 the water is somewhere between 1.024 and 1.028.
If the device is set to ppt or PSU and it reads 35, the water is somewhere between 33 and 37.

That is the limiting accuracy of that particular device.

Just keep the number consistent.

 

[esquare]

Seems like you're saying I was reading it correctly. Maybe I worded my question poorly.

No you're not reading it correctly. It has a resolution of 1 in PSU and ppt. It does not give readings in increments between.

Not accounting for the 2 point variance, a resolution of 1 means a reading of 35 could, inreality, mean the sample is anywhere from 34.5 ppt to 35.4 ppt and the reading was rounded to 35.

I just want to make sure I understand this instrument correctly since so many people like it so much. I struggle with refractometers as I find them hard to see but I like being able to use the same instrument between my DT and 2 QT's without fear of contamination of the tanks. While it's hard to see the line on the scale of a traditional refractometer, I can still tell if it's between 1 point increments which, it appears, the Milwaukee cannot do.