Refractometer Calibration Liquid Possibly Faulty

RainboWBacoN420 · Sep 25, 2016

Hey all,
I've been using a ATC refractometer for quite some time now. I've always calibrated it using R/O D/I water, but just yesterday I went out and bought myself a Refractometer Calibration Solution by AquaCraft, and from there I've spun myself a massive web of confusion...

Apparently, according to the solution, it has been calibrated completely wrong. I adjusted it to 1.026/ 35 ppt as instructed, afterwards I tested the R/O D/I as sort fail proof paranoia practice, and the blue line is below the 1.000 mark... why? Is the solution faulty? I'm so confused. If the solution is correct, then my salinity has been wrong this whole entire time.

Brew12 · Sep 25, 2016

RainboWBacoN420 said:
Hey all,
I've been using a ATC refractometer for quite some time now. I've always calibrated it using R/O D/I water, but just yesterday I went out and bought myself a Refractometer Calibration Solution by AquaCraft, and from there I've spun myself a massive web of confusion...

Apparently, according to the solution, it has been calibrated completely wrong. I adjusted it to 1.026/ 35 ppt as instructed, afterwards I tested the R/O D/I as sort fail proof paranoia practice, and the blue line is below the 1.000 mark... why? Is the solution faulty? I'm so confused. If the solution is correct, then my salinity has been wrong this whole entire time.

What are you reading for your tank water?

bubbaque · Sep 25, 2016

I went through this and made a post about it a few months back that got a lot of replies. I ended up buying a second refractometer thinking my original one was bad. I got it and it read the same thing. I just ended up buying some frags from my local fish store and tested their salinity with my refractometer and it was reading what the calibration fluid was reading. If the LFS can grow corals just fine with the same salinity as the calibration, I figured so could I. My refractometer still reads < 0 with RODI water but I still only use the calibration fluid.

bif24701 · Sep 25, 2016

What brand are you guys using?

I suspected something was off when I bought a new bottle of this stuff:

The new stuff is way off my baseline. My older bottle is accurate, same brand.

RainboWBacoN420 · Sep 25, 2016

Brew12 said:
What are you reading for your tank water?

I use Natural Seawater, and it usually comes in at about 1.025 (-/+), testing with the Refractometer calibrated to the solution, i get a reading of 1.023...
Which just doesn't seem right at all. The same applies to my tank. The solution seems to calibrate it .002- .003 less than what it should be.

RainboWBacoN420 · Sep 25, 2016

bif24701 said:
What brand are you guys using?

I suspected something was off when I bought a new bottle of this stuff:

The new stuff is way off my baseline. My older bottle is accurate, same brand.

I mentioned it in my first post, same stuff you're using by AquaCraft.

bif24701 · Sep 25, 2016

RainboWBacoN420 said:
I use Natural Seawater, and it usually comes in at about 1.025 (-/+), testing with the Refractometer calibrated to the solution, i get a reading of 1.023...
Which just doesn't seem right at all. The same applies to my tank. The solution seems to calibrate it .002- .003 less than what it should be.

Sea water! Good idea! I live on the gulf, dugh! Lol

bif24701 · Sep 25, 2016

RainboWBacoN420 said:
I mentioned it in my first post, same stuff you're using by AquaCraft.

So you think your stuff is low or high? I think mine is high, way high!
I bough mine from BRS a month ago.

Had a friend use a digital refractometer and it read 1.028!

RainboWBacoN420 · Sep 25, 2016

bif24701 said:
So you think your stuff is low or high? I think mine is high, way high!
I bough mine from BRS a month ago.

Had a friend use a digital refractometer and it read 1.028!

Coming in low. Calibrated it to the instructed level, test my salinity after and it comes in as 1.023 (-/+).

bif24701 said:
Sea water! Good idea! I live on the gulf, dugh! Lol

Lol the Natural Seawater I get comes from Half Moon Bay, but it goes through a filtration process before it arrives at my store.

bif24701 · Sep 25, 2016

When did you purchase it?

maroun.c · Sep 26, 2016

Believe this has to do with calibrating your equipment at a range far from the range your using it at. Somehow the error shots further as you move further away from calibration point. This is why it's recommended to calibrate with a solution close to your tanks salinity and not Rodi. It's also the same with ph calibration solutions where we calibrate with 7and 10, not 4 as our phones range is closer to 7 and 10.
You can try another solution or make your own if you want to make sure.

bif24701 · Sep 26, 2016

maroun.c said:
Believe this has to do with calibrating your equipment at a range far from the range your using it at. Somehow the error shots further as you move further away from calibration point. This is why it's recommended to calibrate with a solution close to your tanks salinity and not Rodi. It's also the same with ph calibration solutions where we calibrate with 7and 10, not 4 as our phones range is closer to 7 and 10.
You can try another solution or make your own if you want to make sure.

I've used other solutions and the new bottle I bought a month ago is not right, verified. So I think he may also have a problem considering we both use the same brand.

Bbaz123456 · Sep 26, 2016

Id trust the solution. Never use ro water for calibrating a refractometer.

cromag27 · Sep 26, 2016

Yup, don't use rodi. it's also best to calibrate it before each use. yeah it's a pain but if you can accuracy.....

RainboWBacoN420 · Sep 26, 2016

cromag08 said:
Yup, don't use rodi. it's also best to calibrate it before each use. yeah it's a pain but if you can accuracy.....

But the RO/DI should always be marked at 1.000, right?
And accuracy is what I'm aiming for, but if a product is giving false readings, putting anyone's investment into their tank at potential risk, then it should definitely be questioned.
I'm gonna have to check a digital Refractometer when I go into work tomorrow and straighten this out. I honestly think the batch I'm using is the problem.

Sully · Sep 26, 2016

Bbaz123456 said:
Id trust the solution. Never use ro water for calibrating a refractometer.

This. The instructions say to use the calibration fluid. To many people use RODI and later find out they've been off all along.

Sully · Sep 26, 2016

RainboWBacoN420 said:
But the RO/DI should always be marked at 1.000, right?
And accuracy is what I'm aiming for, but if a product is giving false readings, putting anyone's investment into their tank at potential risk, then it should definitely be questioned.
I'm gonna have to check a digital Refractometer when I go into work tomorrow and straighten this out. I honestly think the batch I'm using is the problem.

No. That's why the instructions say to use 35 ppt calibration fluid.

aaron23 · Sep 26, 2016

Bbaz123456 said:
Id trust the solution. Never use ro water for calibrating a refractometer.

Why do u say never use RO water to calibrate?

cromag27 · Sep 26, 2016

The further away you are from the target, the larger margin of error. same with ph probes.

RainboWBacoN420 said:
But the RO/DI should always be marked at 1.000, right?
And accuracy is what I'm aiming for, but if a product is giving false readings, putting anyone's investment into their tank at potential risk, then it should definitely be questioned.
I'm gonna have to check a digital Refractometer when I go into work tomorrow and straighten this out. I honestly think the batch I'm using is the problem.

RainboWBacoN420 · Sep 26, 2016

The thing I still don't understand is the natural seawater is always 1.025, and that's all I've been using so my tank should be the same. But when calibrated with the fluid, the results come in at 1.023. How can this be unless the solution is faulty?