Refractometers

[hotashes]

Any idea why once both calibrated at room temp (25°) using calibration fluid 35ppt my D-D and Red Sea Reefer refractometers are offering different salinity readings?

I once heard if a refractometer is lightweight is probably useless!! I know rsr are a trusted brand, however my D-D is heavier and is in sync with my 3rd TMC refractometer!!!!

The RSR is much clearer to read, ***.

Hmmmm.

A.

 

[HolisticBear]

The Red Sea has a horrible reputation, it drifts out of calibration within minutes. Mine is in the garbage, plenty of messages about it.

I am a huge red sea fan, but that product is a fail.

 

[hotashes]

Thanks, I'm glad you can make the bold statement to give your opinion. I prefer honesty

Thanks.

A.

 

[GoVols]

Thanks, I'm glad you can make the bold statement to give your opinion. I prefer honesty

Thanks.

A.

Yeah,
I had an terrible time with the Red Sea meter staying tuned in and it drove me nutz.. ;Wacky

The Vee Gee STX-3 Refractometer with the two little fishes .35 solution is and great combination.

And the Pin Point Salinity monitor is an great choice too.

 

[hotashes]

Not acceptable, especially as they have various salts available, with claims of quick mixing etc. Yet it appears their hardware is a tad off?

Hmmm, yet D-D refractometer and their H2O salt seems decent outfit..

Somebody needs to up their game [emoji23]

A.

 

[Flippers4pups]

I've been using my premium aquatics refractometer for years and years. Calibrates easily and holds setting for months.

 

[hotashes]

I'm thinking, if refractometers are pre set calibrated. Could it be that's the screw are coated by manufacture and we're not really meant to be calibration ourselves.. On the other hand if the manufactures know they will drop calibration, surely they would know the coating will be compromised and then the refractometer becomes redundant due to constant calibration requirements...

Oh wait, that why it's made this way. So the end user has to keep replacing the product. More money to the manufactures in the end...

Hmmm.

A.

 

[Flippers4pups]

I'm thinking, if refractometers are pre set calibrated. Could it be that's the screw are coated by manufacture and we're not really meant to be calibration ourselves.. On the other hand if the manufactures know they will drop calibration, surely they would know the coating will be compromised and then the refractometer becomes redundant due to constant calibration requirements...

Oh wait, that why it's made this way. So the end user has to keep replacing the product. More money to the manufactures in the end...

Hmmm.

A.

We there's a good reason for calibration. The prism inside can be bumped or knocked out of alignment by dropping or hitting the refractometer. Thus needing calibration.

 

[GoVols]

We there's a good reason for calibration. The prism inside can be bumped or knocked out of alignment by dropping or hitting the refractometer. Thus needing calibration.

Don,
I got lazy one time and started to zero out my meter with RO/DI.

3 months later I bought so more .35 solution, and zeroing out, was the wrong call...

 

[HolisticBear]

Somebody needs to up their game [emoji23].

I talked to their rep about it at reef-a-palooza. He apologized and said they've heard multiple complaints and have had discussions with the manufacturer, but they didn't find any problems. He just apologized again and gave me a bunch of free test kits as an apology.

It's frustrating because there are literally dozens of messages on R2R, the BRS unit costs less and has almost completely positive reviews.

Related, BRS now carries three different brands of calibration fluid to allow multiple double-checks.

 

[NY_Caveman]

@hotashes, so they both are calibrated to 35 ppt and read the same, but then different for the tank water? Have you tried calibrating to 0 on each refractometer and then testing the known 35 ppt solution? Also, after testing tank water test the solution again to confirm if it is just drifting. In other words is it not accurate or is it not holding its calibration.

My AquaMaxx refractometer is slightly off each time I use it. I calibrate to 0 ppt with RO/DI each time and it holds while testing old and new water. Just this weekend I had an issue, so mixed up a 35 ppt solution based on Randy’s recipe (http://reefkeeping.com/issues/2004-06/rhf/index.htm). It tested dead on at 35 ppt. So I know my refractometer is accurate if I keep it calibrated.

 

[hotashes]

@hotashes, so they both are calibrated to 35 ppt and read the same, but then different for the tank water? Have you tried calibrating to 0 on each refractometer and then testing the known 35 ppt solution? Also, after testing tank water test the solution again to confirm if it is just drifting. In other words is it not accurate or is it not holding its calibration.

My AquaMaxx refractometer is slightly off each time I use it. I calibrate to 0 ppt with RO/DI each time and it holds while testing old and new water. Just this weekend I had an issue, so mixed up a 35 ppt solution based on Randy’s recipe (http://reefkeeping.com/issues/2004-06/rhf/index.htm). It tested dead on at 35 ppt. So I know my refractometer is accurate if I keep it calibrated.

Hey, cheers for reaching out.... Yes they both hold calibration using .35 fluid, I've not tested using rodi. IMO both holding .35 before and after checking saltwater yet offering different salinity readings is worrying heh

A.

 

[NY_Caveman]

Yes. That is very strange. Why would they read the solution the same and not the sample. You could mix a quick Randy’s solution too from the link I gave (if you have a scale) and test a second known source and see what happens.

 

[SPR1968]

Ok I have both the Red Sea, D-D and Apex (salinity probe) and they all read differently if you let them.

When I first started out I spoke with Kevin at Red Sea about the Refractometer and basically it is extremely sensitive and needs to be calibrated before each use, as per the instructions. I find it particularly sensitive to temperature.

I purchased the D-D after I got Apex as the salinity probe was all over the place compared with my trusty Red Sea Refractometer, so I thought I had better check everything. The problem with the D-D is the scale is very difficult to read, for me anyway.

So, in summary my preference is the Red Sea Refractometer and here is what I do.

I calibrate with 0 RODI (I haven’t found any noticeable/significant difference using the 35ppm fluid and I have both). I leave RODI on the glass for 15 seconds to adjust temperature and then adjust the scale to calibrate.

I then wipe (with my shirt of course! Lol) and add the saltwater, leave for 15 seconds, and then take the reading. Done.

The calibration takes a few seconds once you get used to it.

I now calibrate Apex (I use tank water when Im happy it’s 35ppm instead of Neptune’s calibration fluid which causes wild readings!) according to my Red Rea Refractometer and it’s all line, and on the basis my system thrives, it must be ok.

 

[hotashes]

Yes. That is very strange. Why would they read the solution the same and not the sample. You could mix a quick Randy’s solution too from the link I gave (if you have a scale) and test a second known source and see what happens.

They only read the same in the solution as I calibrate them to read the same, hence from here when saltwater is added they read different....

I will read the link, (although I noticed Randy mentions .35 references for calibration are somewhat favourable) ie being close to NSW numbers, cheers.

A.

 

[hotashes]

Ok I have both the Red Sea, D-D and Apex (salinity probe) and they all read differently if you let them.

When I first started out I spoke with Kevin at Red Sea about the Refractometer and basically it is extremely sensitive and needs to be calibrated before each use, as per the instructions. I find it particularly sensitive to temperature.

I purchased the D-D after I got Apex as the salinity probe was all over the place compared with my trusty Red Sea Refractometer, so I thought I had better check everything. The problem with the D-D is the scale is very difficult to read, for me anyway.

So, in summary my preference is the Red Sea Refractometer and here is what I do.

I calibrate with 0 RODI (I haven’t found any noticeable/significant difference using the 35ppm fluid and I have both). I leave RODI on the glass for 15 seconds to adjust temperature and then adjust the scale to calibrate.

I then wipe (with my shirt of course! Lol) and add the saltwater, leave for 15 seconds, and then take the reading. Done.

The calibration takes a few seconds once you get used to it.

I now calibrate Apex (I use tank water when Im happy it’s 35ppm instead of Neptune’s calibration fluid which causes wild readings!) according to my Red Rea Refractometer and it’s all line, and on the basis my system thrives, it must be ok.

Calibrated before each use [emoji32], was swing arm/thermostat hydrometers this temperamental? I've not been in the hobby long enough to know heh

You're not wrong, I find the D-D hard to read as the print is tiny. Hence why I took a linking to RSR one. However, one thing I did notice of the RSR instrument is that the 35ppt marking is in sync with 1.025 SG. Maybe my eyes are bad lol

A.

 

[norfolkgarden]

Lol, one more source of aggravation in my beautiful 4 foot box of missing money.

Mostly a simple softy/fish tank.
Used several different $10 swing arm hydrometers at the same time for years and took the average. Knew which one normally read high, middle or low. (based on comparing to each other)

Finally got a refractometer. Always zeroed it out with RODI.
Finally bought some calibration fluid from BRS.
With calibration fluid I adjusted the refractometer by .001.
Use the calibration fluid about every 4th time. It is as spot on as I can see. I need to dial out the eye piece to the point where it's almost falling off. Thats *with* reading glasses. [emoji23]
Not really thrilled to know this is the easy one to read. [emoji17]

Lol, now I learn this $50 refractometer isn't the greatest....

Lol, time to go out and mow and edge the yard.

 

[cobast]

Perhaps you guys are forgetting that we are playing with 'elcheapo' instruments. Their accuracy might be ok but their precision is poor. That's why they need regular calibration. If you went to a science lab theirs would probably cost many hundreds of $ or thousands. In many industries instruments are checked prior to each use

 

[Randy Holmes-Farley Verified Community Expert]

Perhaps you guys are forgetting that we are playing with 'elcheapo' instruments. Their accuracy might be ok but their precision is poor. That's why they need regular calibration. If you went to a science lab theirs would probably cost many hundreds of $ or thousands. In many industries instruments are checked prior to each use

I’m not sure many scientists use refractometers at all. I’ve worked in many labs over the decades, and the one time I had reason to want to measure refractive index (of a solid gel material), I had to go to a specialized lab at MIT where they had a bench top refractometer (which did cost thousands and read to more significant figures than the hobby ones reefers use).

I don’t recall ever even seeing another refractometer in a chemistry lab. [emoji3]

 

[alton]

I am still old school from 1982 till now it is a glass hydrometer for me, Tropic Marin makes a nice one. I can say I do not hear the horror stories of 15 years ago and refractometers, so they must be getting better?