Recommendation for Salinity Tester

[rmorris_14]

I was driving myself nuts with this. I spent so much checking and re checking and calibrating my refractometer and then cross checking with other devices. I’ve since picked one device and one calibration solution. It’s seawater. And decided to just stick to focusing on consistency.

 

[Dennis Cartier]

Further to Randy's point about the Orion's. They are excellent meters (I have 5 of them ). The probes (conductivity cells) are the hard part to find working, in good condition and for a reasonable price.

If you are searching Ebay, you will find plenty of 2 electrode probes, and lots of probes only useful for freshwater ranges. Those will not work for a reef tank. So always check the model number of the probe and look it up online to confirm that it fits your meter, it has 4 electrodes, and that it goes to a range, usually 200ms, that is high enough to measure saltwater.

PM me if you need help confirming a listing is for the correct type. I promise not to poach it.

 

[Randy Holmes-Farley Verified Community Expert]

I use the beer refractometer with the seawater calibration fluid.
I don't check it to anything. I think consistency is best....as long as ur doing it the same and such. Friend uses the Milwaukee and had checked my salinity. Please don't use the old swing arm hydrometer. LOL. I used those when I started.... worked though. Lol.
D

How do you do that? Just match the standard? Do you try to read units off it?

 

[monkeyCmonkeyDo]

The seawater says right on it what to calibrate it to...

 

[Acros]

I use Milwaukee MA887. In fact, I have 2 of them, and they read precisely the same as each other every single time. The key is to let the water rest on the reader for 1 min before taking the reading; that way, the temperature stabilizes.

look up this video:

 

[Randy Holmes-Farley Verified Community Expert]

The seawater says right on it what to calibrate it to...

In what units, and what do you do after that?

Specific gravity on a beer refractometer does not match specific gravity on a seawater refractometer.

 

[monkeyCmonkeyDo]

Mine is a seawater ats refractometer. Sorry. They came from beer breweries 1st is my understanding and point.
D

 

[monkeyCmonkeyDo]

In ppm. Think it's 32

 

[BanjoBandito]

I use a Milwaukee and I love it. It's rock solid.

 

[Randy Holmes-Farley Verified Community Expert]

OK, a seawater refractometer is different than a beer refractometer (ethanol/water). Were good now.

I discuss the latter here:

Refractometers and Salinity Measurement - REEFEDITION

Title photo by R2R member Rskillz By Randy Holmes-Farley Salinity is one of the most important parameters measured in reef aquaria. It controls not only the salt balance between an organism and its surrounding environment, but also the levels of a host of ions Read more here...

www.reefedition.com

Brix Refractometers

A commonly manufactured type of refractometer is called a Brix refractometer. Its scale usually reads in Brix, or % Brix (percent Brix). These refractometers are used in many industries to measure the concentration of sugar in water such as in the soft drink industry. They can be used to measure seawater’s salinity, but are not always precise enough around the range of seawater’s refractive index to be useful. A resolution of 0.2% Brix is common, and that is borderline acceptable for the reasons detailed below.

Table 4 shows the relationship between seawater salinity, refractive index and % Brix. If a refractometer has a resolution (not accuracy, but resolution, which is the finest amount it can distinguish) of 0.2 % Brix, then that translates to about +/- 1 ppt. So the best resolution would translate to 35 ppt seawater reading 34-36 ppt, which may be adequate for reef aquarists. A Brix refractometer that reads 0 to 10 % Brix with a resolution of 0.1% Brix might be a fine choice for determining seawater salinity in a reef aquarium, (although they are not inexpensive). Some Brix refractometers have a resolution of 0.5 % Brix or even 1% Brix, and they would not be suitable choices.

 

[Randy Holmes-Farley Verified Community Expert]

I use Milwaukee MA887. In fact, I have 2 of them, and they read precisely the same as each other every single time.

They do not claim to be very accurate, however.

Milwaukee MA887 Digital Salinity Refractometer

The Milwaukee Instruments digital salinity refractometer is ideal for saltwater aquarium professionals and enthusiasts.

milwaukeeinstruments.com

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

 

[monkeyCmonkeyDo]

This is awsome! Ty. It is My bed time unfortunately. See you all later today. Need to come back and read this.
Lol.
D

 

[python1369]

I know it sounds strange but I use a refractometer and green star polyps. My GSP will not extend their tentacles to the full length. Then I check salinity with the refractometer. They never steer me wrong.

 

[Randy Holmes-Farley Verified Community Expert]

I know it sounds strange but I use a refractometer and green star polyps. My GSP will not extend their tentacles to the full length. Then I check salinity with the refractometer. They never steer me wrong.

In what range do you notice this effect?

 

[Acros]

They do not claim to be very accurate, however.

Milwaukee MA887 Digital Salinity Refractometer

The Milwaukee Instruments digital salinity refractometer is ideal for saltwater aquarium professionals and enthusiasts.

milwaukeeinstruments.com

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

I understand that they are not very accurate. Do you happen to know if they are reliable?

 

[tpirovol]

For the Tropic Marine one , I find it best to use the second tube it comes in and fill it up about 2/3 the way and place the TP in it. That way there is no water movement .

 

[patrickb]

Basically, use whatever you want, but calibrate it with a Tropic Marin hydrometer. Physics doesn't lie!

 

[Randy Holmes-Farley Verified Community Expert]

I understand that they are not very accurate. Do you happen to know if they are reliable?

Only what reefers say, which seems mixed.

It is easy to check them with a standard, even though they must be calibrated with RO/DI.

 

[Steve27]

I have been using an American marine pinpoint salinity monitor for the past several months. Super easy and accurate so far.

 

[BradVol]

They do not claim to be very accurate, however.

Milwaukee MA887 Digital Salinity Refractometer

The Milwaukee Instruments digital salinity refractometer is ideal for saltwater aquarium professionals and enthusiasts.

milwaukeeinstruments.com

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

This was my concern. If I'm aiming for 34 it could be 36 and it could be 32. But all the anecdotal reports are that it reads the same reliably all the time, although some claim it's .002 off in SG (I'm not sure what the corresponding ppt is).
On the hydrometer it sounds like I need to get a bigger cylinder than it comes with to fill with water and test it in. I haven't looked up the temp conversion part yet but I'm curious how far off it will be if the water temp is 78 or even 80 in the summer.

This has been an awesome discussion though and I'm learning, so it's fun.