DIY Refractometer calibration fluid

[jonbar1]

I made a solution of 3.65 grams sodium chloride to 96.35 grams RO water to calibrate my refractometer. When I put it on my refractometer do I dial the refractometer until it lines up with 35 ppt?

Sorry if this is a stupid question, I just want to be positive before I adjust my tanks accordingly. Thank you in advance!

 

[Randy Holmes-Farley]

I made a solution of 3.65 grams sodium chloride to 96.35 grams RO water to calibrate my refractometer. When I put it on my refractometer do I dial the refractometer until it lines up with 35 ppt?

Sorry if this is a stupid question, I just want to be positive before I adjust my tanks accordingly. Thank you in advance!

Yes. :)

 

[VexedTomb792]

@Randy Holmes-Farley I bought some 35ppt calibration solution from continuum aquatics after reading that you shouldn’t calibrate your refractometer on zero with RO/DI water (which I’ve done for years). I used the solution and set the calibration screw until it matched on the eyepiece. Turns out that the 1.024 tank that I always thought I had is possibly a 1.026 tank. I then cleaned the slide off and used RO water to take a reading, the blue/white split was now quite a way above zero. That made me nervous, and I’m staring to doubt myself, should I stick to the new method of calibration or revert to my tried and tested method?

 

[Randy Holmes-Farley]

@Randy Holmes-Farley I bought some 35ppt calibration solution from continuum aquatics after reading that you shouldn’t calibrate your refractometer on zero with RO/DI water (which I’ve done for years). I used the solution and set the calibration screw until it matched on the eyepiece. Turns out that the 1.024 tank that I always thought I had is possibly a 1.026 tank. I then cleaned the slide off and used RO water to take a reading, the blue/white split was now quite a way above zero. That made me nervous, and I’m staring to doubt myself, should I stick to the new method of calibration or revert to my tried and tested method?

A brine refractometer, which most are, will not read zero correctly if perfectly calibrated to 35 ppt. So I expect all is as expected.

 

[VexedTomb792]

A brine refractometer, which most are, will not read zero correctly if perfectly calibrated to 35 ppt. So I expect all is as expected.

Thank you for that. It’s a DD H2ocean refractometer. Is that what you would expect from that one?

 

[skiergd011013]

@Randy Holmes-Farley I bought some 35ppt calibration solution from continuum aquatics after reading that you shouldn’t calibrate your refractometer on zero with RO/DI water (which I’ve done for years). I used the solution and set the calibration screw until it matched on the eyepiece. Turns out that the 1.024 tank that I always thought I had is possibly a 1.026 tank. I then cleaned the slide off and used RO water to take a reading, the blue/white split was now quite a way above zero. That made me nervous, and I’m staring to doubt myself, should I stick to the new method of calibration or revert to my tried and tested method?

I tried two store bought solutions against Randys DIY, and both werent even close to the DIY. One of them was from bulk reef supply, and the other from amazon. I would be careful about trusting that commercial solution.

 

[VexedTomb792]

I tried two store bought solutions against Randys DIY, and both werent even close to the DIY. One of them was from bulk reef supply, and the other from amazon. I would be careful about trusting that commercial solution.

The only thing that’s giving me any comfort is that my tank water reads exactly the same as the calibration solution now I’ve used it to calibrate so either the the solution is 1.024 and not 35ppt or my tank was always 35ppt but I was reading it at 1.024. I hate days where I’m less sure of something at the end of the day than I was at the beginning :-(

 

[Aaron Stone]

I tried two store bought solutions against Randys DIY, and both werent even close to the DIY. One of them was from bulk reef supply, and the other from amazon. I would be careful about trusting that commercial solution.

I guess this begs the question: how do you know your solution was accurate?

 

[skiergd011013]

The only thing that’s giving me any comfort is that my tank water reads exactly the same as the calibration solution now I’ve used it to calibrate so either the the solution is 1.024 and not 35ppt or my tank was always 35ppt but I was reading it at 1.024. I hate days where I’m less sure of something at the end of the day than I was at the beginning :-(

Its probably fine if everything looks happy. I do know that both of my bottles were testing quite low. I calibrated my milwaukee digital refract with randys DIY 1.026 standard, and then tested the commercial standards. One of them measured 30 or 31 ppt. Im also pretty sure one of them was the continuum bottle from amazon. If you can use a Grams scale and some table salt, it is very easy to make some.

 

[skiergd011013]

I guess this begs the question: how do you know your solution was accurate?

I used randys exact instructions, made up a bottle, and it tested 1.027 on my milwaukee, calibrated with RODI. I then made up a second bottle of randys standard, to double check my work, and it measured the exact same as the first one. So i slapped a label on my milwaukee that "1.027 = 1.026".

 

[Aaron Stone]

Its probably fine if everything looks happy. I do know that both of my bottles were testing quite low. I calibrated my milwaukee digital refract with randys DIY 1.026 standard, and then tested the commercial standards. One of them measured 30 or 31 ppt. Im also pretty sure one of them was the continuum bottle from amazon. If you can use a Grams scale and some table salt, it is very easy to make some.

Did you calibrate your scale? What is its accuracy?

This is always the rabbit hole I go down when I think of DIY reference solutions. What is the purity of your salt, how accurate is your scale... Makes my head hurt, and also make me realize that close enough is sometimes close enough (above being the case in point)

 

[VexedTomb792]

Its probably fine if everything looks happy. I do know that both of my bottles were testing quite low. I calibrated my milwaukee digital refract with randys DIY 1.026 standard, and then tested the commercial standards. One of them measured 30 or 31 ppt. Im also pretty sure one of them was the continuum bottle from amazon. If you can use a Grams scale and some table salt, it is very easy to make some.

That’s really crap though, continuum is quite a large company that produces masses of reef and aquatics products they are stocked by all the major sites in the UK, see link below

Continuum Aquatics

 

[Aaron Stone]

I used randys exact instructions, made up a bottle, and it tested 1.027 on my milwaukee, calibrated with RODI. I then made up a second bottle of randys standard, to double check my work, and it measured the exact same as the first one. So i slapped a label on my milwaukee that "1.027 = 1.026".

Good method, double checking

 

[skiergd011013]

That’s really crap though, continuum is quite a large company that produces masses of reef and aquatics products they are stocked by all the major sites in the UK, see link below

Continuum Aquatics

Maybe i got a bad bottle??? I tested it a few times, and into the trash it went. After that, i personally do not trust the store bought ones and use Randys.

 

[skiergd011013]

Did you calibrate your scale? What is its accuracy?

This is always the rabbit hole I go down when I think of DIY reference solutions. What is the purity of your salt, how accurate is your scale... Makes my head hurt, and also make me realize that close enough is sometimes close enough (above being the case in point)

Sure did. My scale uses a 500g calibration weight to calibrate it. I used regular iodized table salt as per his instructions. I am PICKY with my tank, and was quite thorough.

 

[gbroadbridge]

I used randys exact instructions, made up a bottle, and it tested 1.027 on my milwaukee, calibrated with RODI. I then made up a second bottle of randys standard, to double check my work, and it measured the exact same as the first one. So i slapped a label on my milwaukee that "1.027 = 1.026".

That's exactly what you should do.

I did a sticker for mine as well a couple of years back (mine was 1.028 == 1.026)

 

[JayM]

@Randy Holmes-Farley I bought some 35ppt calibration solution from continuum aquatics after reading that you shouldn’t calibrate your refractometer on zero with RO/DI water (which I’ve done for years). I used the solution and set the calibration screw until it matched on the eyepiece. Turns out that the 1.024 tank that I always thought I had is possibly a 1.026 tank. I then cleaned the slide off and used RO water to take a reading, the blue/white split was now quite a way above zero. That made me nervous, and I’m staring to doubt myself, should I stick to the new method of calibration or revert to my tried and tested method?

The Vee Gee STX-3 is what I use, and is the only refractometer I've seen where the manufacturer says to calibrate to "ZERO" with RODI. It was 3x the cost of most others, but was spot-on out of the box and has remained that way so far.

 

[gbroadbridge]

The Vee Gee STX-3 is what I use, and is the only refractometer I've seen where the manufacturer says to calibrate to "ZERO" with RODI. It was 3x the cost of most others, but was spot-on out of the box and has remained that way so far.

The Milwaukee also is calibrated to zero using DI water.
You can then use Randy's home brew calibration fluid to check the accuracy of the device and determine any necessary offset.

 

[skiergd011013]

The Vee Gee STX-3 is what I use, and is the only refractometer I've seen where the manufacturer says to calibrate to "ZERO" with RODI. It was 3x the cost of most others, but was spot-on out of the box and has remained that way so far.

The milwaukee digital ones are the same....calibrate to zero with rodi. So i did that, then measured my DIY standard, and got 1.027.

 

[VexedTomb792]

The milwaukee digital ones are the same....calibrate to zero with rodi. So i did that, then measured my DIY standard, and got 1.027.

Ok so after reading the instructions from DD H2ocean (my refractometer) I’m even more confused.
@skiergd011013
@JayM
@Randy Holmes-Farley
Have a read, I really don’t think I’ve grasped the concept

Refractometer instructions | D-D The Aquarium Solution

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