refractometer......

beelzebob · 12/27/2006, 12:26 PM

so i just got a refractometer, and apon reading all the callibration jarble, i gots myself an idea.

can i callibrate my refractometer against an already callibrated one? i.e. goin to my lfs, put the same water on both, and callibrate mine to read the same as theirs?

papagimp · 12/27/2006, 12:29 PM

Sure you could, now the real question is theirs really calibrated or are they just going to tell you it is? If they look at you and ask "calibrated?" then don't use theres, lol.

bertoni · 12/27/2006, 01:23 PM

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

That article tells how to make a calibration solution. The PinPoint 53 mS conductivity solution will also work. Other brands probably won't, though.

Willie_6 · 12/27/2006, 01:42 PM

Do not use another refractometer to calibrate yours. Buy some distilled water. Test it. It should read 0. Adjust it to 0 if it reads something else.

bdare · 12/27/2006, 02:31 PM

Use freshly made RO/DI water to calibrate...

Fermat · 12/27/2006, 02:41 PM

As has been discussed on many threads here, calibrating at 0 is sometimes not sufficient to calibrate the refractometer. The problem has to do with the fact that some refractometers have the scale designed based on table salt rather than sea salt, which has slightly different refractive properties. This ultimately can lead to the refractometer being off by as much as 0.003 at or around the salinity of sea water. Ideally the refractometer should be calibrated with a solution at or near the salinity of sea water, such as the PinPoint 53 mS conductivity solution (which our resident chemist has been kind enough to research and confirm that it will also have the same refractive properties of natural sea water).

The DIY solution is a very good screening test to see if you have a refractometer that is in bad need of calibration. In my case, the DIY solution showed my refractometer was perfect, and later I confirmed this with the PinPoint solution.

beelzebob · 12/27/2006, 02:44 PM

http://www.reefcentral.com/forums/sh...refractometers

this is why i ask.

RO/DI water doesn't calibrate the majority of refratometers out there correctly.

if they are off a smige, and you callibrate them w FW, the smige would be on the marine reading.

callibrating with water that has a veryfied SG the smige would be on the FW side.

so exatally what profanity removed is wrong with calibrating against another refractometer?

papagimp · 12/27/2006, 02:52 PM

It seems to me like they just don't like the added hassle of locating a properly calibrated refractometer to compare readings too. Doing it yourself at home is quicker and easier. But if the refrac you are comparing to is accurate, no reason you can't.

Fermat · 12/27/2006, 02:59 PM

Exactly papa... How can you be sure they have calibrated correctly? A couple months ago I asked my lfs about the pinpoint solution, and they told me straight out that they don't carry it. Without that, I'd be suspicious that they calibrated correctly no matter what they told me.

Of coure, if they happen to have the solution and used it to calibrate their refractometers, I'd think they'd be happy to let you use a few drops to calibrate your own.

beelzebob · 12/27/2006, 02:59 PM

im goin for the lfs because ima 23yr old college student. the only measuring devices i have are a half cup, and empty 12oz beer bottles.

i suck at mixing. even when i do my tests i sometimes add to many drops.

my LFS is pretty spot on about everything (except charging me $50 for GSP) so im more than confident in their accuracy.

plus they have 3 refractometers on hand, maybe ill go for an average.

papagimp · 12/27/2006, 03:05 PM

Yeah beezlebob, some of those LFS are awfully proud of their GSP's, lol.

beelzebob · 12/27/2006, 05:07 PM

so i gottanother question.

premises

so a refractomter is callibrated to determine the amount of a specific dissolved solid in a solution, right?

the callibration of a refractometer is the callibration of the refractment of light first through the water then the crystal, and this refractment is changed by the amount of dissolved solids in the water, right?

but normal fresh water has a trace amount of a ton of dissolved solids in it naturally right?

RO/DI processes remove the trace amounts of dissolved solids in the water because the can be harmful to our lil glass edens, right?

so then questions

so, if i measured the same water w/ the same refractometer before and after RO/DI, shouldn't the reading change because the are "scientifically" a different solution?

then, wouldn't it make more sense to callibrate 0ppt salinity with the crappy water or water from a FW tank? cause it has stuff in it, but not salt?

bertoni · 12/27/2006, 08:21 PM

If the other refractometer has been calibrated, using it that way is fine.

The refractometer is measuring the refractive index of the water, and RO-DI and tapwater likely would have a different refractive index, but the difference is likely too small to be measured, for most people.

12/27/2006, 12:26 PM	#1
beelzebob Moved On Join Date: Nov 2006 Location: Boulder, Colorado. USA Posts: 213	refractometer...... so i just got a refractometer, and apon reading all the callibration jarble, i gots myself an idea. can i callibrate my refractometer against an already callibrated one? i.e. goin to my lfs, put the same water on both, and callibrate mine to read the same as theirs?

12/27/2006, 12:29 PM	#2
papagimp COMAS Rocks! Join Date: Apr 2006 Location: Oklahoma City, OK Posts: 8,185 Blog Entries: 2	Sure you could, now the real question is theirs really calibrated or are they just going to tell you it is? If they look at you and ask "calibrated?" then don't use theres, lol. __________________ 58g Softie & 75g Stoney Member, Central Oklahoma Marine Aquarium Society Current Tank Info: 58g Mixed Reef Project - Started June 2011

12/27/2006, 01:23 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	http://www.reefkeeping.com/issues/2004-06/rhf/index.php That article tells how to make a calibration solution. The PinPoint 53 mS conductivity solution will also work. Other brands probably won't, though. __________________ Jonathan Bertoni

12/27/2006, 01:42 PM	#4
Willie_6 Registered Member Join Date: Mar 2005 Location: Ohio Posts: 1,439	Do not use another refractometer to calibrate yours. Buy some distilled water. Test it. It should read 0. Adjust it to 0 if it reads something else. __________________ 75 gal. reef tank in the making. Snails, Emerald Crabs, Scarlet Crabs,a cleaner shrimp. Midas Blenny, Scooter Blenny, ocellaris clown, Mandarin. Current Tank Info: 75 gal fish and rock, 432w 8 bulb T-5 lights, Deltec Skimmer MCE 600, 25 gal Fuge/Sump, Ro/Di from Buckeye Supply.

12/27/2006, 02:31 PM	#5
bdare Salty Dude Join Date: Feb 2006 Location: Rockwall, TX Posts: 1,322 Blog Entries: 3	Use freshly made RO/DI water to calibrate... __________________ 220 Mixed Reef GeoCaRx, GHL Profilux 4, Octopus Skimmer, Kessil 360X 2 x Maxspect Gyre XF350

12/27/2006, 02:41 PM	#6
Fermat Registered Member Join Date: Nov 2006 Location: Pennsylvania, US Posts: 239	As has been discussed on many threads here, calibrating at 0 is sometimes not sufficient to calibrate the refractometer. The problem has to do with the fact that some refractometers have the scale designed based on table salt rather than sea salt, which has slightly different refractive properties. This ultimately can lead to the refractometer being off by as much as 0.003 at or around the salinity of sea water. Ideally the refractometer should be calibrated with a solution at or near the salinity of sea water, such as the PinPoint 53 mS conductivity solution (which our resident chemist has been kind enough to research and confirm that it will also have the same refractive properties of natural sea water). The DIY solution is a very good screening test to see if you have a refractometer that is in bad need of calibration. In my case, the DIY solution showed my refractometer was perfect, and later I confirmed this with the PinPoint solution.

12/27/2006, 02:44 PM	#7
beelzebob Moved On Join Date: Nov 2006 Location: Boulder, Colorado. USA Posts: 213	http://www.reefcentral.com/forums/sh...refractometers this is why i ask. RO/DI water doesn't calibrate the majority of refratometers out there correctly. if they are off a smige, and you callibrate them w FW, the smige would be on the marine reading. callibrating with water that has a veryfied SG the smige would be on the FW side. so exatally what profanity removed is wrong with calibrating against another refractometer? Last edited by bertoni; 12/27/2006 at 08:18 PM.

12/27/2006, 02:52 PM	#8
papagimp COMAS Rocks! Join Date: Apr 2006 Location: Oklahoma City, OK Posts: 8,185 Blog Entries: 2	It seems to me like they just don't like the added hassle of locating a properly calibrated refractometer to compare readings too. Doing it yourself at home is quicker and easier. But if the refrac you are comparing to is accurate, no reason you can't. __________________ 58g Softie & 75g Stoney Member, Central Oklahoma Marine Aquarium Society Current Tank Info: 58g Mixed Reef Project - Started June 2011

12/27/2006, 02:59 PM	#9
Fermat Registered Member Join Date: Nov 2006 Location: Pennsylvania, US Posts: 239	Exactly papa... How can you be sure they have calibrated correctly? A couple months ago I asked my lfs about the pinpoint solution, and they told me straight out that they don't carry it. Without that, I'd be suspicious that they calibrated correctly no matter what they told me. Of coure, if they happen to have the solution and used it to calibrate their refractometers, I'd think they'd be happy to let you use a few drops to calibrate your own.

12/27/2006, 03:05 PM	#11
papagimp COMAS Rocks! Join Date: Apr 2006 Location: Oklahoma City, OK Posts: 8,185 Blog Entries: 2	Yeah beezlebob, some of those LFS are awfully proud of their GSP's, lol. __________________ 58g Softie & 75g Stoney Member, Central Oklahoma Marine Aquarium Society Current Tank Info: 58g Mixed Reef Project - Started June 2011

12/27/2006, 05:07 PM	#12
beelzebob Moved On Join Date: Nov 2006 Location: Boulder, Colorado. USA Posts: 213	so i gottanother question. premises so a refractomter is callibrated to determine the amount of a specific dissolved solid in a solution, right? the callibration of a refractometer is the callibration of the refractment of light first through the water then the crystal, and this refractment is changed by the amount of dissolved solids in the water, right? but normal fresh water has a trace amount of a ton of dissolved solids in it naturally right? RO/DI processes remove the trace amounts of dissolved solids in the water because the can be harmful to our lil glass edens, right? so then questions so, if i measured the same water w/ the same refractometer before and after RO/DI, shouldn't the reading change because the are "scientifically" a different solution? then, wouldn't it make more sense to callibrate 0ppt salinity with the crappy water or water from a FW tank? cause it has stuff in it, but not salt?

12/27/2006, 08:21 PM	#13
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	If the other refractometer has been calibrated, using it that way is fine. The refractometer is measuring the refractive index of the water, and RO-DI and tapwater likely would have a different refractive index, but the difference is likely too small to be measured, for most people. __________________ Jonathan Bertoni