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View Poll Results: NaCl Refract or NSW Refract & How do you Calibrate? | |
QUESTION NUMBER ONE-----DON'T PICK
|    | 0 | 0% | |
NaCl Refractometer
|    | 9 | 56.25% | |
NSW Refractometer
|    | 2 | 12.50% | |
QUESTION NUMBER TWO-----DON'T PICK
|    | 0 | 0% | |
I calibrate to zero with RO/DI water
|    | 15 | 93.75% | |
I calibrate to 35 PPT with 53 microsiemens fluid
|    | 1 | 6.25% | |
I calibrate to 35 PPT with RHF's homemade standard
| | 0 | 0% | 
11-08-2006, 09:41 PM
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#1 (permalink)
| | Blue Ringed Angel
Join Date: Sep 2003 Location: St. Louis
Posts: 1,575
   
|  Refractometer Calibration
Most of us are using a refractometer calibrated for Sodium Chloride (NaCl) as opposed to NSW including myself. This has always posed a problem because these refractometers are .0015 too low in SG when calibrated using RO/DI water or distilled. I've always calibrated to zero and just mentally made the adjustment.
The other option is to use a 53 mS solution and then calibrate to 35 ppt/1.0265 SG as opposed to zero and make no adjustment whatsoever. You can also make your own solution. Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com
The reason I'm interested in this poll is because Randy Holmes-Farley and Boomer have been testing a lot of refracts recently in preparation for an article and they've found many as far off as .003 SG. A properly made refractometer should only be off .0015 SG. That's spooky. Imagine thinking you're at 1.026 when you're really at 1.023.
Please pick a choice for question number 1....What type of refractometer do you have?
Please pick a choice for question number 2.....How do you calibrate? _________ Curt 
Last edited by inwall75 : 11-08-2006 at 09:50 PM.
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11-08-2006, 09:52 PM
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#2 (permalink)
| | Blue Ringed Angel
Join Date: Sep 2003 Location: St. Louis
Posts: 1,575
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Well, I can see that this poll isn't going to work. Option 1 on question 2 was supposed to be, "I calibrate to zero with RO/DI water".
If any mod's know how to fix this, please do so. Until this happens, please use option 1 if you use RO/DI water or distilled water. | |
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11-08-2006, 10:58 PM
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#3 (permalink)
| | KingFish
Join Date: Dec 2000 Location: Pt. Richmond, Ca. Age: 38
Posts: 7,330
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(I fixed it. I am looking into the permission issue.) | |
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11-08-2006, 11:00 PM
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#4 (permalink)
| | Blue Ringed Angel
Join Date: Sep 2003 Location: St. Louis
Posts: 1,575
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You da man Matt!!!
Thanks
C | |
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11-09-2006, 01:31 PM
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#5 (permalink)
| | KingFish
Join Date: Dec 2000 Location: Pt. Richmond, Ca. Age: 38
Posts: 7,330
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No prob. 
Looks like you need some more votes so I am bumping this. | |
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11-09-2006, 02:46 PM
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#6 (permalink)
| | Vlamingii Tang
Join Date: Mar 2004 Location: Utica, NY Age: 49
Posts: 1,887
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I calibrate to zero with RO/DI water _________ 150 Gallon Reef 2-400w MH 2-110w VHO Actinic's, Moon lights, 250lbs LR,2-CPR CS150 overflows, 55 gallon sump/Refugium,auto-top-off, 6-Stage RO/DI Filter, E.T.S.S.600 Skimmer, Red sea 100 ozoneizer, Pinpoint ORP/PH controller, MRC-CR2 Calcium Reactor, 80w R/Lifeguard UV filter, 1/2 hp Chiller, Medusa 2 stage Temp Controller, Iwaki MD-100RLT Return Pump | |
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11-09-2006, 02:51 PM
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#7 (permalink)
| | Blue Ringed Angel
Join Date: Sep 2003 Location: St. Louis
Posts: 1,575
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Quote: |
Originally Posted by Matt Rogers No prob.
Looks like you need some more votes so I am bumping this. | Yeah, it shocks me. I was expecting more discussion.
Most people think that their refractometers are accurate when 99.9% of them I've seen in the hobby are low by .0015 SG brand new right out of the box because they are calibrated to NaCl as opposed to NSW. | |
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11-09-2006, 02:53 PM
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#8 (permalink)
| | Astrea Snail
Join Date: Sep 2006 Location: Outside of Seattle, WA
Posts: 57
Karma: 8
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Interesting, when I set up my current system in June, I purchased a refractometer from the LFS. The same one that came out with a truck load of RO/DI premixed water to get us up and running. There was no discussion about different types of refractometers, just a brief training session on using, read, cleaning, and & calabration checks (using RO/DI).
After reading the instructions that came with it, the MFG confirms that the refractometer is calabrated with RO/DI.
So, every week when I run out some RO/DI for the make up tank, I do a quick 'cal' check. I have had to adjust it only once since purchase, and that was just a very small tweek.
So, do I have a NaCl or NSW refractometer , I don't know..... | |
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11-09-2006, 03:10 PM
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#9 (permalink)
| | Blue Ringed Angel
Join Date: Sep 2003 Location: St. Louis
Posts: 1,575
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More than likely, it's NaCl. I only know of two NSW refracts that are affordable enough for hobbiests. Refractometers National Microscope.com - New and Used Microscopes, Refractometers and Supplies
The most common model that hobbiests are using is the RHS-10atc model which is produced by two separate companies. (The second company copied the first company's model number). If you have this model (from either company), it is calibrated to NaCl and not NSW. | |
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11-09-2006, 03:22 PM
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#10 (permalink)
| | Blue Ringed Angel
Join Date: Sep 2003 Location: St. Louis
Posts: 1,575
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Quote: |
Originally Posted by grubbsj After reading the instructions that came with it, the MFG confirms that the refractometer is calabrated with RO/DI. | Here's where it get's tricky. You can calibrate a NSW refractometer with RO/DI water and it will be 100% accurate. The instructions for NaCl refracts also say to calibrate with RO/DI water or Distilled water and those will be inaccurate by .0015 SG by doing so.
There are refractometers for alcohol, blood, urine, honey, you name it. | |
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