Refractometer calibration tempature question

reef_doug · #1 01/04/2008, 04:41 PM

I just picked up some Pinpoint 53ms Calibration Fluid for my refractomer w/ ATC. The solution says 53ms at 77F.

Do I need to have the solution and ambient tempature at 77F to accurately calibrate the refractomer at 35ppt?

Is there a temp / calibration conversion chart (ie my soultion and ambient temp at 72F ?)

surfjeepzx · #2 01/04/2008, 07:32 PM

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

Also, just go to the top of the chemistry section and about 3 posts down there's a post about chemistry articles. Click on that and scan down to the topic of salinity. That's where I found the link above.

Randy Holmes-Farley · #3 01/04/2008, 08:10 PM

It should not matter much with ATC, but I'd try to use it close to normal room temp, say in the 70's.

reef_doug · #4 01/05/2008, 01:36 AM

Thanks Randy! My refractometer was reading +.003 before calibration. Could it be possible that it was this far off?

It's adjusted now to 35 ppt with 53mS in the mid 70F.

mixed_reefer · #5 01/05/2008, 02:00 AM

I have a milwaukee mr100atc. If i dont let the temperature of the solution and the refractometers prism equalize in temperature, i get bogus readings.

Billybeau1 · #6 01/05/2008, 02:06 AM

Quote:

Originally posted by reef_doug
Thanks Randy! My refractometer was reading +.003 before calibration. Could it be possible that it was this far off?

It's adjusted now to 35 ppt with 53mS in the mid 70F.

Yes, that is very normal. Happened to me and many others. Some refracts just cannot be calibrated with ro/di, regardless what the manufacturer states.

Mine was .003 off just like yours. As Randy said as long as you are in the 70's your calibration is good if the refract has ATC (which most do these days).