High Quality Refractometer Recommendations?

[painter1982]

I find conductivity meters that have a probe on a cord much more user friendly than either hydrometers or refractometers. :)

Can you point me to your means of calibrating or testing a conductivity meter?

 

[Randy Holmes-Farley Verified Community Expert]

Can you point me to your means of calibrating or testing a conductivity meter?

The logistics depend entirely on the meter, but I make my diy 53 mS/cm (35 ppt seawater) standard, read it with the meter, and set it to read 53 mS/cm or 35 ppt.

Often, I do not bother to recalibrate, but just make the manual correction I show above. I equilibrate my standard (53 mS/cm) in the meter for several minutes (to be sure it is temp equilibrated) and get a reading. Then if it says 52.5 mS/cm, I correct subsequent readings manually by multiplying by 53/52.5

 

[Aspect]

Calibrate it however you want. Then test 35 ppt. If it reads 34 ppt, then you multiply all readings with that calibration by 35/34.

If you use specific gravity, then use the last digits only . For example, 35 ppt is about sg = 1.0264. If it reads 1.025 then multiply all readings by 26.4/25, and put the one in front again.

The only way I can see to calibrate is with distilled or rodi water, id like to calibrate at 35 ppt though

 

[Randy Holmes-Farley Verified Community Expert]

The only way I can see to calibrate is with distilled or rodi water, id like to calibrate at 35 ppt though

I don’t think you can based on the electronics, but what I suggested works exactly like recalibration, except it’s a little more work.

 

[smoorman11]

Any reason to think I shouldn't trust my 20 year old TM hydrometer? Can they go out of calibration? Can the scale move from vibration Etc?

 

[Randy Holmes-Farley Verified Community Expert]

Any reason to think I shouldn't trust my 20 year old TM hydrometer? Can they go out of calibration? Can the scale move from vibration Etc?

It is likely fine unless the paper moved (or was mismanufactured originally). It is easy to confirm it with a cheap DIY standard:

https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

 

[smoorman11]

It is likely fine unless the paper moved (or was mismanufactured originally). It is easy to confirm it with a cheap DIY standard:

https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/

Will do. Thanks

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing. :)

 

[X-37B]

I have used the TM for quite awhile. I use my conductivity meter now and use the TM to check it.
The two units are within 0.0003 of each other.
Not sure why more people are not using these over other methods.

 

[jabberkaycee]

I got a little confused while reading through all 5 pages, but believe the BRS refractometer I’m using is a true seawater unit. The scale shows 35 ppt salinity equals 1.0264 specific gravity. I’ve calibrated with BRS’s Refracto Juice (35ppt) that comes free with the purchase. Once calibrated, it shows exactly zero when checking with RO/DI water. It does drift over time, so I recalibrate as needed.

I also have a Milwaukee MA887 that has never worked - It just will not calibrate. When trying to calibrate with RO/DI water, is just shows” LO”. It reads ppt at 5, and specific gravity at 1.003.

 

[Gumbies R Us]

I got a little confused while reading through all 5 pages, but believe the BRS refractometer I’m using is a true seawater unit. The scale shows 35 ppt salinity equals 1.0264 specific gravity. I’ve calibrated with BRS’s Refracto Juice (35ppt) that comes free with the purchase. Once calibrated, it shows exactly zero when checking with RO/DI water. It does drift over time, so I recalibrate as needed.

I also have a Milwaukee MA887 that has never worked - It just will not calibrate. When trying to calibrate with RO/DI water, is just shows” LO”. It reads ppt at 5, and specific gravity at 1.003.

I use something similar to this with basic calibration solution and have never had any issues!

 

[carri10]

These posts on refractometers confuse me, I have to say. I have a hanna handheld, the white one with the blue buttons. I have a homemade calibration solution (super easy). The hand held gets calibrated once every couple of week or so and is rarely that far out. Its super simple, super reliable and super quick. Why does everyone use a refractometer? Am I missing something?

 

[Gumbies R Us]

These posts on refractometers confuse me, I have to say. I have a hanna handheld, the white one with the blue buttons. I have a homemade calibration solution (super easy). The hand held gets calibrated once every couple of week or so and is rarely that far out. Its super simple, super reliable and super quick. Why does everyone use a refractometer? Am I missing something?

I just use a refractometer because it was cheap. That was the main reason I used one

 

[slingfox]

These posts on refractometers confuse me, I have to say. I have a hanna handheld, the white one with the blue buttons. I have a homemade calibration solution (super easy). The hand held gets calibrated once every couple of week or so and is rarely that far out. Its super simple, super reliable and super quick. Why does everyone use a refractometer? Am I missing something?

I have been through three Hanna salinity checkers and many pouches of calibration solution. It is not super accurate. How I found that out is comparing results to my periodic ICP. It is not super far off, but if you want dead on accuracy I don’t think you can rely on the Hanna. If your unit lines up with ICP testing then great, but it is doubtful.

Here is my salinity vs ICP as an example of accuracy:

 

[EricR]

These posts on refractometers confuse me, I have to say.

Same here. Visual refractometers just seem like a giant pain to me.

I use the TM hydrometer, mainly.

I also have the Hanna digital that I use to quick match new saltwater salinity to my tank water.
The only issue I've ever had with my Hanna unit is with the Hanna calibration fluid, so I switched to using Randy's DIY standard and no more problems.
I like mine but seems like many have issues so might just be luck of the draw (poor QC on mass-produced unit or something).

 

[Randy Holmes-Farley Verified Community Expert]

I have been through three Hanna salinity checkers and many pouches of calibration solution. It is not super accurate. How I found that out is comparing results to my periodic ICP. It is not super far off, but if you want dead on accuracy I don’t think you can rely on the Hanna. If your unit lines up with ICP testing then great, but it is doubtful.

Here is my salinity vs ICP as an example of accuracy:

Perhaps calibrating with a different and better standard would help. :)

 

[Aspect]

These posts on refractometers confuse me, I have to say. I have a hanna handheld, the white one with the blue buttons. I have a homemade calibration solution (super easy). The hand held gets calibrated once every couple of week or so and is rarely that far out. Its super simple, super reliable and super quick. Why does everyone use a refractometer? Am I missing something?

I had used the Hanna checker and it almost caused my tank to crash as it was reading around 4-5 ppt lower than the actual tanks salinity. I've been using the Milwaukee digital refractometer since this post and found it to be very consistent and accurate.

 

[mcarroll]

These posts on refractometers confuse me, I have to say. I have a hanna handheld, the white one with the blue buttons. I have a homemade calibration solution (super easy). The hand held gets calibrated once every couple of week or so and is rarely that far out. Its super simple, super reliable and super quick. Why does everyone use a refractometer? Am I missing something?

They should confuse you IMO....to me those posts don't make (physics) sense.

The advantage of the refractometer is that they are non-electrical....thus should never require "routine" recalibration. Why? Because something would physically have to move inside the refractometer in order for it to become "off calibration". What force will cause the set screw, with a clamping ring locked in place, to move?

I have no idea what law of physics is being violated to allow all these folks to have "drifting refractometers".

Drifting with ordinary usage is, however, a trait of electronic sensors.

Unless you treat your refractometer violently (enough to move the stationary prism inside) or change its calibration via the screw, there's no reason I know to explain it moving out of calibration.

Seeing LOTS of people have good experiences with them online was the reason I bought mine....and mine has never (pushing 20 years now) gone out of calibration unless the calibration screw was fiddled with by a child who didn't know better (literally).

The only rationale I can conceive to explain those posts is user error.

Some refractometers do not have ATC (automatic temperature compensation) and some do....my guess is that some folks who have ATC don't use it properly (takes time). And some folks who don't have it, don't realize it. Temperature changes from reading to reading can generate differing results even with the same actual salinity level.

The refractometer alternative I like is the old-fashioned swing-arm hydrometer....its issues, such as they are, are well known and easy to work with to still get accurate readings.

Floating glass hydrometers would be nicer if they weren't glass....nothing wrong with their ability, they're just too fragile IMO – they would be better suited for the protected environment of the lab.

For what it's worth, Spotte (Captive Seawater Fishes, 1992) only talks about conductivity meters, refractometers and hydrometers (giving excellent breakdowns of each).....noting that hydrometers are the easiest as well as sufficient for husbandry purposes.

The supposed issue with refractometers is a recent fad as far as I'm concerned. Maybe related to the $10 units that seem to be for sale now and which weigh almost nothing...are they made out of paper?!!? In these Amazon years, some folks may need a lesson on what "too cheap" is. But I didn't pay a lot (maybe $30-50?) for my refractometer from Marine Depot and it's been many, many years now. BRS (who bought Marine Depot) still sells reasonably priced models for around $40 to $70....perhaps buying those would make all the difference.

A good link that explores the ACTUAL pros and cons of refractometers while not relying on hobby fads or vendors selling calibration fluid for the facts like AI and most online posts do:
https://www.researchgate.net/profil...tions-Limitations-And-Future-Perspectives.pdf

 

[carri10]

I have been through three Hanna salinity checkers and many pouches of calibration solution. It is not super accurate. How I found that out is comparing results to my periodic ICP. It is not super far off, but if you want dead on accuracy I don’t think you can rely on the Hanna. If your unit lines up with ICP testing then great, but it is doubtful.

Here is my salinity vs ICP as an example of accuracy:

Hiya, I always use a homemade calibration solution - it's dirt cheap and when you make it yourself you know it is correct.

Randy's DIY is an option here, you just need scales, salt, and RO water. That's it. No more need to buy any more pouches!

 

[carri10]

They should confuse you IMO....to me those posts don't make (physics) sense.

The advantage of the refractometer is that they are non-electrical....thus should never require "routine" recalibration. Why? Because something would physically have to move inside the refractometer in order for it to become "off calibration". What force will cause the set screw, with a clamping ring locked in place, to move?

I have no idea what law of physics is being violated to allow all these folks to have "drifting refractometers".

Drifting with ordinary usage is, however, a trait of electronic sensors.

Unless you treat your refractometer violently (enough to move the stationary prism inside) or change its calibration via the screw, there's no reason I know to explain it moving out of calibration.

Seeing LOTS of people have good experiences with them online was the reason I bought mine....and mine has never (pushing 20 years now) gone out of calibration unless the calibration screw was fiddled with by a child who didn't know better (literally).

The only rationale I can conceive to explain those posts is user error.

Some refractometers do not have ATC (automatic temperature compensation) and some do....my guess is that some folks who have ATC don't use it properly (takes time). And some folks who don't have it, don't realize it. Temperature changes from reading to reading can generate differing results even with the same actual salinity level.

The refractometer alternative I like is the old-fashioned swing-arm hydrometer....its issues, such as they are, are well known and easy to work with to still get accurate readings.

Floating glass hydrometers would be nicer if they weren't glass....nothing wrong with their ability, they're just too fragile IMO – they would be better suited for the protected environment of the lab.

For what it's worth, Spotte (Captive Seawater Fishes, 1992) only talks about conductivity meters, refractometers and hydrometers (giving excellent breakdowns of each).....noting that hydrometers are the easiest as well as sufficient for husbandry purposes.

The supposed issue with refractometers is a recent fad as far as I'm concerned. Maybe related to the $10 units that seem to be for sale now and which weigh almost nothing...are they made out of paper?!!? In these Amazon years, some folks may need a lesson on what "too cheap" is. But I didn't pay a lot (maybe $30-50?) for my refractometer from Marine Depot and it's been many, many years now. BRS (who bought Marine Depot) still sells reasonably priced models for around $40 to $70....perhaps buying those would make all the difference.

A good link that explores the ACTUAL pros and cons of refractometers while not relying on hobby fads or vendors selling calibration fluid for the facts like AI and most online posts do:
https://www.researchgate.net/profil...tions-Limitations-And-Future-Perspectives.pdf

Good post, thanks. When I started out, I bought a glass hydrometer, thinking it would be my "gold standard" calibration. Used it once and the paper scale inside moved! So that was that. Since then an electronic pen, a big pot of a calibration solution I KNOW is right, and I'm good. After having researched a little into what salinity actually is, and what we are actually measuring in our multi solute water, I realised the actual number really isn't important (within obvious limits) - keeping that number constant (assuming the solute concentrations reamin approx const) is key. And hobby level anything adds error bars that we can't do much about, but must be aware of before we act.