What are you using to test salinity?

[t5Nitro]

It is likely a fine device. I had one that was accurate, but I will note that some people touting the accuracy have never actually verified if it is true or not.

But they have substantial drawbacks and I think conductivity meters are much more user friendly option. Temperature corrections needed, the fact that it needs deep water to float in, cannot be used in otehr settings (such as limewater potency),and the fact that it is not easy to read at a glance while doing other things (say, when acclimating new creatures) made me rarely use mine.

I use and liked an Orion Model 128 conductivity meter with a 4 electrode probe.

I wouldnt mind having a reliable conductivity meter. Is the A122 model the current version similar to yours? Checking Thermo Fisher on this link.

Conductivity Meters | Thermo Fisher Scientific - US

Conductivity benchtop meter,conductivity tester,benchtop conductivity meter,conductivity measurement, portable conductivity meter, portable meter, field samples for conductivity

www.thermofisher.com

 

[Oregon Grown Reef]

I use the Misco seawater refractometer. Definitely the most expensive one mentioned, but it's as close to lab grade as you can get before paying lab prices. I calibrate mine after every use because it takes 15 seconds, but you don't have to. I figure why not get the best reading every time. It's the only one I've had where I trusted the results every time. When I first got it, I wanted to see how consistent it was if I did a bunch of readings without calibrating after each use. I tested 4 of my tanks, new saltwater, and retested, and all of them came back the same number.

 

[t5Nitro]

I use the Misco seawater refractometer. Definitely the most expensive one mentioned, but it's as close to lab grade as you can get before paying lab prices. I calibrate mine after every use because it takes 15 seconds, but you don't have to. I figure why not get the best reading every time. It's the only one I've had where I trusted the results every time. When I first got it, I wanted to see how consistent it was if I did a bunch of readings without calibrating after each use. I tested 4 of my tanks, new saltwater, and retested, and all of them came back the same number.

Looks like a great tool. Thanks! Will pick one up.

 

[Reefinmike]

That is untrue.

First, weighing is not a super accurate way to determine salinity. It was discarded as a preferred method decades ago. Not just because it is hard to do, but because it is not accurate.
This is trickier than it might seem, and not worth doing at home, but it can work and was the standard back in the 1800's to early 1900's. There's a detailed historical description in Chemical Oceanography by Millero. It requires pretty high heat (480 degrees C) since you need to dehydrate the salts that precipitate as crystalline hydrates (magnesium chloride, magnesium sulfate, etc.). Unfortunately, that also will convert carbonates and bicarbonates into oxides and hydroxides, causing weight loss. You also lose some chloride, bromide and iodide (as HCl, HBr, and HI and some Cl2 and Br2). Boric acid also vaporizes. All of these require corrections (or prevention) if high accuracy is a goal.


Conductivity is by FAR the most precise and accurate method, and is what chemical oceanographers use. It is the whole basis of the current salinity scale: 35 PSU is seawater that matches the conductivity of a particular specified concentration of potassium chloride (32.4356 grams in a mass of 1 kg of solution (=53 mS/cm).) in water.

Well, I learned something new today! I did create a 2L batch of precision weighed SG reference solution using your DIY article and my hydrometers were spot on 1.0264sg @25C

 

[Rubberfrog]

I use a refractometer from BRS

 

[thatmanMIKEson]

I have a couple of those cylinders and similar things to measure alcohol content for my homemade distilling operation (I do it where it’s legal).

so much easier to use than the ATC/brs. Maybe I’m biased because I’m very familiar with it

Its not legal anywhere in the U.S good luck with ATF

 

[boboyo]

Since this thread is revived : I upgraded to a digital Hanna salinity/temperature reader. One of the greatest investments I’ve made for my reef tank. Borrowed one off a friend to do hyposalinity since mine didn’t go under 1.015 and realized I can’t live without one. Makes life so easy

 

[William Morris]

Has anyone heard or used the Tropic Marin hydrometer? Supposedly extremely accurate with zero calibration needed. Only downsides are size and how fragile it is.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

I switched over to the TM hydrometer 6 weeks ago. Works great and I can verify with the Red Sea Refractometer.
Great for mixing up salt too.
Don't need the large cylinder they recommend - just turn the pumps off and measure.

 

[JosephM]

I switched over to the TM hydrometer 6 weeks ago. Works great and I can verify with the Red Sea Refractometer.
Great for mixing up salt too.
Don't need the large cylinder they recommend - just turn the pumps off and measure.

I actually ended up going with that one and I absolutely love it. No more guessing if it’s calibrated or not

 

[GK3]

BRS refractometer. Wish I hadn't spent extra for the lighted one. Doesn't work well for me. Never use it..any room, window or flash light works better. Not bothered enough to replace it though.

Calibrate with refractojuice every week or so. Have to adjust it maybe once every 3-4 months.

Just got mine today. That LED light on it is worthless. I shut the lights off and tried the led, line doesn’t show. Turn some lights back on, and you can faintly see the line because what seeps through around their led. Has anyone used this and gotten their Led to work?

 

[GK3]

This may sound OCD, but I’m really annoyed by the fact the HANA probe uses the abbreviation ppt for parts per thousand. This is the abbreviation for parts per trillion. I have seen this cause serious confusion, especially to people new I the reef hobby. Chemists don’t abbreviate parts per thousand for this reason. At least it has SG mode though, that’s a plus.

So not OCD but it does depend on what field you are in. You are 100% correct that PPT is part per trillion. However, in oceanography, they deal more with part per thousand than they do part per trillion. So if you walked into a chem lab and wrote down ppt it would be 10^-12. However if you got on a boat with an oceanographer and wrote ppt, they would read it as 10^-3. I think that’s why it’s done this way on the Hana.

 

[thatmanMIKEson]

So not OCD but it does depend on what field you are in. You are 100% correct that PPT is part per trillion. However, in oceanography, they deal more with part per thousand than they do part per trillion. So if you walked into a chem lab and wrote down ppt it would be 10^-12. However if you got on a boat with an oceanographer and wrote ppt, they would read it as 10^-3. I think that’s why it’s done this way on the Hana.

boom, nice i like it :]