Refractometer Caibration Solution

[GoPitt88]

So, I had an old bottle (2 years old) of this:

so I went online and bought this:

The solution from BRS is reading 33ppt when calibrated with the old Aqua Craft solution, so I figured maybe it was due to evaporation over time. But I wasn't convinced......so I just bought a new bottom of Aqua Craft solution, and it reads exactly the same as the older bottle of Aqua Craft. Hmmm..... Is the stuff from BRS off by 2ppt? Which one should I trust? I'm thinking Aqua Craft. I'm surprised how different the solution from BRS is. Any thoughts? Thanks [emoji16]

 

[redfishbluefish]

That crazy. If you can, have a reefer friend or LFS test your calibration solutions with their refractometer. I have two different brands of calibration, and they are both the same. Something is not right.

 

[GoPitt88]

The reason for concern is that my tank is at 1.0255 when calibrated against the Aqua Craft, but it's at 1.027 when calibrated against the BRS solution. Ugh!

 

[GoPitt88]

That crazy. If you can, have a reefer friend or LFS test your calibration solutions with their refractometer. I have two different brands of calibration, and they are both the same. Something is not right.

What do you use to calibrate?

 

[GoVols]

So, I had an old bottle (2 years old) of this:

so I went online and bought this:

The solution from BRS is reading 33ppt when calibrated with the old Aqua Craft solution, so I figured maybe it was due to evaporation over time. But I wasn't convinced......so I just bought a new bottom of Aqua Craft solution, and it reads exactly the same as the older bottle of Aqua Craft. Hmmm..... Is the stuff from BRS off by 2ppt? Which one should I trust? I'm thinking Aqua Craft. I'm surprised how different the solution from BRS is. Any thoughts? Thanks [emoji16]

@HolisticBear

(lol)
Please chime in...

 

[HolisticBear]

@HolisticBear

(lol)
Please chime in...

BRS had a bad batch, the number is EXP041822, mentioned in this post. A big gotcha with the top solution (any solution) is you need to shake it well before every use.

If you don't, after a number of uses and in your case two-years, the calibration solution can become more concentrated than 35.

EDIT: To BRS's credit, I think they sent a mass email to every customer that purchased that lot and removed the offending lot from their inventory.

 

[GoPitt88]

BRS had a bad batch, the number is EXP041822, mentioned in this post. A big gotcha with the top solution (any solution) is you need to shake it well before every use.

If you don't, after a number of uses and in your case two-years, the calibration solution can become more concentrated than 35.

EDIT: To BRS's credit, I think they sent a mass email to every customer that purchased that lot and removed the offending lot from their inventory.

OMG! That's the batch I have! See the pic. Just sent BRS an email. Thank you SO much!

 

[redfishbluefish]

Problem solved! Good job @HolisticBear


FWIW, here are the two I use:

 

[GoPitt88]

Glad I bought a new batch of Aqua Craft solution after the batch from BRS read low. My new batch of Aqua Craft solution reads the same as my old batch of Aqua Craft solution. So now I feel confident that my tank salinity is exactly where I want it. Phew! [emoji16]

 

[redfishbluefish]

FYI, my Aqua Craft is eight plus years old...and reads the same as the PinPoint.

 

[GoPitt88]

FYI, my Aqua Craft is eight plus years old...and reads the same as the PinPoint.

Awesome! That's good to know [emoji106]

 

[pecan2phat]

I have 35ppt calibration fluid with an expiration date of 2004 and just referenced it with 25ppt calibration fluid, still good!

 

[HolisticBear]

I don't think solution goes "bad".

I made the mistake of not shaking a AquaCraft bottle prior to use. I used it almost weekly for 6-8 months, so maybe 1/3 - 1/4 empty. I bought a new AquaCraft bottle and the old one 'read 1ppm high". So just remember to shake it and I think you're good to go.

They are cheap, so grab a second one every now and then. You can also calculate salinity via your ICP report and it should roughly match as well.

 

[ReefSCTim]

I use that same Aqua Craft solution to calibrate my refractometer. Once calibrated, it says my tank salt is at 30 ppm. My new Neptune salinity probe say it is at 48.1 ppm. Sure hope this gets easier soon!!