Which Refractometer Calibration Fluid?

shrimped · Nov 13, 2019

Hello I've been using the same refractometer for about 4 years now without calibrating it since the first day of use so i think... no... its definitely time to calibrate it. I have no idea what calibration fluid should I get so Im listening to suggestions!

ChaseBurke · Nov 13, 2019

BRS refractojuice

Reesj · Nov 13, 2019

Refractrometers operate linearly. Your RO water is better than any stuff some one else ships over.

Anchor · Nov 13, 2019

ChaseBurke said:
BRS refractojuice

its as good as any.. important part. consistency.

shrimped · Nov 13, 2019

ChaseBurke said:
BRS refractojuice

Thank you but I forgot to add that i would prefer one from Amazon because BRS require shipping price (I think like $5 or sumin) and its free when u spend $29 i think

Reesj said:
Refractrometers operate linearly. Your RO water is better than any stuff some one else ships over.

I was considering this but i heard some people had problems with using RODI for calibration

Anchor said:
its as good as any.. important part. consistency.

Hm then is this one from amazon ok or the bright well one?

lavoisier · Nov 13, 2019

Distilled water works just fine and you can pick it up at the grocery store.

Reesj · Nov 13, 2019

shrimppsacc said:
I was considering this but i heard some people had problems with using RODI for calibration

Then there is a problem with that refractormeter. Its not the fault of the RO water calibration.
These are the small things companies market to fool people to steal cash off of them imo.

shrimped · Nov 13, 2019

lavoisier said:
Distilled water works just fine and you can pick it up at the grocery store.

i got some at home, ill go try it out thank you

Reesj said:
Then there is a problem with that refractormeter. Its not the fault of the RO water calibration.
These are the small things comanies market to steal cash off people imo.

My refractometer is this one off of amazon. is it known for inaccuracy? I'll also go try calibrating it with my RODI water when i get home. How do i know if it has a problem or not?

shred5 · Nov 13, 2019

I have about 5 bottle of RO calibration fluid and they all measure different from each other....

madweazl · Nov 13, 2019

Calibrate your refractometer every time you use it; no point in having a precision tool when you have no idea what it's actually reading.

As for which solution, I've been using this for about three years with good results. I purchased another bottle a few months back to check the original and they were both inline with one another (original bottle is at least three years old).

shrimped · Nov 13, 2019

madweazl said:
Calibrate your refractometer every time you use it; no point in having a precision tool when you have no idea what it's actually reading.

As for which solution, I've been using this for about three years with good results. I purchased another bottle a few months back to check the original and they were both inline with one another (original bottle is at least three years old).

thank you! ill order one rn. I also forgot i got a few ICP tests from the RAP Cali goodie bag lol. ill send one out soon

Bayareareefer18 · Nov 13, 2019

You can get accurasea on Amazon. Works well

shrimped · Nov 13, 2019

Bayareareefer18 said:
You can get accurasea on Amazon. Works well

Thank you. ill go check those out

hotdrop · Nov 13, 2019

I think randy had a recipe use sodium chloride and distilled water. It will get you close enough that inconsistent temperature will swing you beyond that

ReefLab · Nov 13, 2019

i got this one off amazon. I dont have anything to check it against but my corals seem happy. One thing i will say is do not use RO water. I thought mine was calibrated with RO water and it was off my 3ppt which is significant. You want your calibration standard to be as close to your desired value as possible

shrimped · Nov 13, 2019

hotdrop said:
I think randy had a recipe use sodium chloride and distilled water. It will get you close enough that inconsistent temperature will swing you beyond that

ReefLab said:
i got this one off amazon. I dont have anything to check it against but my corals seem happy. One thing i will say is do not use RO water. I thought mine was calibrated with RO water and it was off my 3ppt which is significant. You want your calibration standard to be as close to your desired value as possible

ill check those out Thank you

Larry L · Nov 13, 2019

Please read @Randy Holmes-Farley 's article about refractometers and calibration:

http://reefkeeping.com/issues/2006-12/rhf/index.php

In particular the section titled "Imperfect Refractometer Calibration: Slope Miscalibration". It explains why you are much better off calibrating with a solution closer to natural seawater than you are calibrating using RO water.

drawman · Nov 13, 2019

I will say I've found multiple brands to be inconsistent with brand new bottles.

I thought the BRS version was made by brightwell I wonder if anyone can comment.

Randy Holmes-Farley · Nov 13, 2019

Reesj said:
Refractrometers operate linearly. Your RO water is better than any stuff some one else ships over.

Not true.

There are two big reasons that is fallacious, but the most problematic is that most refractometers sold to hobbyists are brine refractometers repurposed to use in seawater. Such a refractometer, even if PERFECTLY manufactured and PERFECTLY calibrated with RO water WILL NECESSARILY be off for measuring seawater. That is the scam by resellers. Not the use of a standard.

The second reason, of course, is that cheap refractometers are unlikely to be perfect, and calibrating with an appropriate 35 ppt standard makes them suitable for 35 ppt measurements.

Reesj · Nov 14, 2019

Randy Holmes-Farley said:
Not true.

There are two big reasons that is fallacious, but the most problematic is that most refractometers sold to hobbyists are brine refractometers repurposed to use in seawater. Such a refractometer, even if PERFECTLY manufactured and PERFECTLY calibrated with RO water WILL NECESSARILY be off for measuring seawater. That is the scam by resellers. Not the use of a standard.

The second reason, of course, is that cheap refractometers are unlikely to be perfect, and calibrating with an appropriate 35 ppt standard makes them suitable for 35 ppt measurements.

After you done calibrating with these 35 ppt soloutions Randy, did you ever had occsations where the refractro meter did not show 0 or almost 0 for RO or 0 TDS water? If so can you please tell what kind of values you normally get ?