Bring refractometers to CMAS meeting

[mkirda]

I will be bringing a calibration solution to the meeting today.

Regards.
Mike Kirda

 

[mkirda]

Continuing for December meeting

Continuing for December meeting

Will continue to offer this at the next meeting at Rod's Reef in December.

Bring in your refractometer to have it tested against a known salinity calibration solution. This is mixed up in a lab to 35ppt at an accuracy level beyond what a refractometer sold in the hobby is capable of measuring.

Regards.
Mike Kirda

 

[Douglas LEHMAN]

Hello Mike
Thanks for the tune up, am I good to go...

 

[Pufferpunk]

For anyone that wants to travel to the Ohare area, I have a bottle & am willing to test out anyone's refractometer. You also get a free tank tour!

 

[mkirda]

I would urge anyone using a commercially available calibration solution to bring it to the next meeting. I would like to have a larger sample pool.

Regards.
Mike Kirda

 

[rickyb]

I missed this thread before the meeting :hmm3:

Can a refractometer be calibrated against one that is accurate or recently calibrated?

 

[mkirda]

<a href=showthread.php?s=&postid=8577995#post8577995 target=_blank>Originally posted</a> by rickyb
I missed this thread before the meeting :hmm3:

Can a refractometer be calibrated against one that is accurate or recently calibrated?

Sure. If one that was calibrated to against a known standard, you could measure your salinity with it, then adjust the other one to the same reading using the same salt water. You could calibrate yours against either of Doug's.

I would also add that at least one sample of a commercially available calibration solution was quite a bit off. I'd like other samples to test at the next meeting. If you have them, please bring them as well to the next meeting. The more samples we have, the better.

Regards.
Mike Kirda

 

[sellout007]

Cant you just use fresh RO water to set it to 0?

 

[mkirda]

<a href=showthread.php?s=&postid=8578426#post8578426 target=_blank>Originally posted</a> by sellout007
Cant you just use fresh RO water to set it to 0?

My personal refractometer is off by 2ppt at seawater salinity when set to zero using ultrapure water. You really need to measure at two points, not just one, or calibrate against a known standard that is close to seawater salinity.

So, no, you cannot be absolutely sure that a refractometer zeroed out using fresh RO water will be measuring correctly at 35ppt.

Regards.
Mike Kirda

 

[sellout007]

Thats interesting, I would have never guessed that it would be off. Whats the reasoning it doesnt work?

Not doubting you, just trying to understand. O)

 

[mkirda]

Whats the reasoning it doesnt work?

Poor quality control?

 

[sellout007]

Haha ok.