Refractometer calibration?

[Circle10]

I've always used Ro/di to calibrate my refractometer, friend let me barrow some accurasea calibration fluid and I was off by almost 1.5 ppt!!!!???!!! :to_pick_ones_nose3: did I use correctly?? Compared against friends and really close after calibration ?? I thought my tank was at 1.026 more like 1.024/1.025 ..how do you guys calibrate?????

 

[pandimus]

I've always used Ro/di to calibrate my refractometer, friend let me barrow some accurasea calibration fluid and I was off by almost 1.5 ppt!!!!???!!! :to_pick_ones_nose3: did I use correctly?? Compared against friends and really close after calibration ?? I thought my tank was at 1.026 more like 1.024/1.025 ..how do you guys calibrate?????

Some guys use calibration fluid. But my marine depot refractometer says to use rodi in the instructions

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[pciscott]

35ppt calibration fluid and to be accurate it needs to be the same temp as your tank. I leave a bottle floating in both my sumps so I can calibrate.

 

[Paranoiattack91]

35ppt calibration fluid and to be accurate it needs to be the same temp as your tank. I leave a bottle floating in both my sumps so I can calibrate.

What he said. My refractometer says not to use rodi.

 

[Adrock]

you want to calibrate your instrument with a fluid that is similar to what you will be testing for accuracy

 

[Adrock]

35ppt calibration fluid and to be accurate it needs to be the same temp as your tank. I leave a bottle floating in both my sumps so I can calibrate.

solid advice ...as always +1 PCI

 

[watchguy123]

Intuitively, one would think calibration at any set point would work, 0 or 35 ppt or anywhere in between. But it seems using a calibration at or near ideal parameter reduces the margin of error.

I thought that most refractometers temperature compensate?

 

[pandimus]

So does it vary from manufacturer to manufacturer?

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[russ13]

You can use RODI but you will be calibrating it way out of the level you are trying to measure. That's why it's better to use calibration fluid

 

[pandimus]

http://www.reefcentral.com/forums/showthread.php?p=18291595

Good thread explains why you should use calibration fluid. I guess they wrote the manual not based on one specific user, but rather a basic baseline

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[turbonut]

It's all about refractive index, the ri is different between rodi/distilled then an actual calibration solution. All that matters imho is that whatever you use be it rodi or a calibrating solution is that you keep it stable.


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[Circle10]

Thnx guys , started last night to do 5 gal water changes to bring salinity up to 1.026 (currently @1.024+). My salinity has allways been stable so tank has never had a issue , guess it's always a good idea to double check your test equipment on a regular basis.if friend wouldn't have barrowed mine and complained it was off I wouldn't have thought about it.. Going to calibrate my PH probe tonight too!

 

[solitude127]

Now the question is... How do you know that the calibration fluid that's supposed to be 35ppt is actually 35ppt? What if there's evaporation? Now your supposed 35ppt is actually now 38ppt

 

[Circle10]

Now the question is... How do you know that the calibration fluid that's supposed to be 35ppt is actually 35ppt? What if there's evaporation? Now your supposed 35ppt is actually now 38ppt

I hope so ? It was a new bottle of TLF accurasea cal fluid @ 78deg (Floated in sump for two hours)

 

[turbonut]

Now the question is... How do you know that the calibration fluid that's supposed to be 35ppt is actually 35ppt? What if there's evaporation? Now your supposed 35ppt is actually now 38ppt

Exactly ?


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[pandimus]

http://www.reefkeeping.com/issues/2004-06/rhf/

Diy calibration fluid. Just make more when you suspect it's bad

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[solitude127]

I hope so ? It was a new bottle of TLF accurasea cal fluid @ 78deg (Floated in sump for two hours)

but how long do you think that fluid was in a hot warehouse and/or delivery truck?

 

[Circle10]

but how long do you think that fluid was in a hot warehouse and/or delivery truck?

how do you calibrate ???
I'm going bike riding to Venice beach today maybe I should calibrate at the freshest source, or maybe bring with me to Hawaii this summer vacation ?:laugh:

 

[solitude127]

how do you calibrate ???
I'm going bike riding to Venice beach today maybe I should calibrate at the freshest source, or maybe bring with me to Hawaii this summer vacation ?:laugh:

I usually use both RO/Di and calibration fluid.