Go Back   Home > Atlanta Reef Club Forums > Reef Discussion
Register / Join the ARC Community Chat Gallery MemberMap Forums Search Today's Posts Mark Forums Read

Visit all of our sponsors


Reply
 
Thread Tools Search this Thread Display Modes
Old 08-20-2012, 8:52 AM   #1
velocityoflove velocityoflove is offline
 
Join Date: Mar 2012
Age: 27
Posts: 140
City: Buford
State: GA
Occupation: Petco Mall of Georgia
Other Interests: television production
refractometer calibration- distilled or calibration fluid?

I felt like my refractometer was giving me funny readings. It would go out of calibration, and my salt mix "recipe" would read high. I've never dropped it.
I went to my lfs, and we got the same reading. I've checked it at two stores. Both of these stores calibrate with RO or distilled water.

I went to a store that calibrated with calibration fluid and they got a completely different reading, that my salt was very low.

My fish and coral seem fine. My refractometer reads fine (I calibrated with distilled). Should I not trust my reading? I'm worried about my salt, but I'm not sure what to do.

Reply With Quote
Old 08-20-2012, 8:56 AM   #2
Rdnelson Rdnelson is offline
Atlanta Reef Club Member
ARC Member
 
Join Date: Jul 2011
Posts: 7,758
City: Cumming
State: GA
Occupation: Electrical Contractor
Other Interests: Home Improvement, Woodworking.
Real Name: Rich
When calibrating any precision device, it is always best to calibrate at levels close to those you will be testing. In otherwords, calebrating to a solution that has a salinity close to whay you want your salt mix to be will give you much more accurate readings.

Reply With Quote
Old 08-20-2012, 9:55 AM   #3
kilralpine kilralpine is offline
Atlanta Reef Club Member
ARC Member
 
Join Date: Apr 2012
Posts: 552
City: Cumming
State: GA
Occupation: Server Production Assistant
Other Interests: Cars and Gaming
Real Name: Alex Arceneaux
I would probably do as he said, find a store with some 1.025 calibration fluid or like 1.020 and then reverse check it against RO and make sure its reading dead 0. I think at that point I would trust your meter. You said it was different between the two stores?? When they checked their own salt levels? or with calibration fluids??

Reply With Quote
Old 08-20-2012, 10:26 AM   #4
ichthyoid ichthyoid is offline
ARC Member
 
Join Date: May 2009
Posts: 2,373
City: Canton
State: GA
Occupation: Medical Sales
Other Interests: molecular biophysics
Quote:
Originally Posted by rdnelson99 View Post
When calibrating any precision device, it is always best to calibrate at levels close to those you will be testing. In otherwords, calebrating to a solution that has a salinity close to whay you want your salt mix to be will give you much more accurate readings.
+1
Few instruments are accurate over their entire range. By using DI water you are calibrating at the extreme bottom of the refractometer's range.

The inaccuracy is usually caused by the device being nonlinear. That is, there is often an 'S' shaped response over the measuring range. Knowing this, you will want to calibrate near the middle of the devices range.

You also want to use a device where the quantity to be measured is near the center of the devices measuring range, as Rich mentioned above.

Reply With Quote
Old 08-20-2012, 10:52 AM   #5
velocityoflove velocityoflove is offline
 
Join Date: Mar 2012
Age: 27
Posts: 140
City: Buford
State: GA
Occupation: Petco Mall of Georgia
Other Interests: television production
Quote:
Originally Posted by kilralpine View Post
I would probably do as he said, find a store with some 1.025 calibration fluid or like 1.020 and then reverse check it against RO and make sure its reading dead 0. I think at that point I would trust your meter. You said it was different between the two stores?? When they checked their own salt levels? or with calibration fluids??


I went to a store to have the salt mix I made for my water change tested. They got 1.027, the same as I was reading. My salt mix usually gets me a 1.025 every time. They checked their calibration there with RO water. I went to another place that used calibration fluid. They read my tank at 1.018. They also checked their calibration. I went home and calibrated mine with distilled water, then tested my tank which read 1.025.

Reply With Quote
Old 08-20-2012, 11:10 AM   #6
kilralpine kilralpine is offline
Atlanta Reef Club Member
ARC Member
 
Join Date: Apr 2012
Posts: 552
City: Cumming
State: GA
Occupation: Server Production Assistant
Other Interests: Cars and Gaming
Real Name: Alex Arceneaux
I would safely assume that your probably in the range of that 1.027 reading and your 1.025 reading. The calibration fluid stores 1.018 seems so out of line; I would place my bet on they just messed up the calibrating somehow. Some refractometers are designed to be used with RO or Distilled. Just remember to keep it simple, test a single batch multiple times and make sure your not getting different readings with your refract. Then base your WC water and your tank water off of your own meter and keep it as stable as possible.

Edit: Also with the testing of the salt batch, how do you determine that your "salt mix" is always 1.025?

Reply With Quote
Old 08-20-2012, 1:14 PM   #7
velocityoflove velocityoflove is offline
 
Join Date: Mar 2012
Age: 27
Posts: 140
City: Buford
State: GA
Occupation: Petco Mall of Georgia
Other Interests: television production
Quote:
Originally Posted by kilralpine View Post

Edit: Also with the testing of the salt batch, how do you determine that your "salt mix" is always 1.025?
I test it every time to make sure, of course. I take 5 Gallons of RO minus 10 cups, and add 2 cups of salt.

Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 users and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mag calibration fluid source to test Elos kit? thewarbrd Reef Discussion 2 03-25-2010 7:16 AM
Refractometer calibration: RODI/Distilled or saline? Can't use both. Acroholic Reef Discussion 12 05-29-2009 3:29 PM
PH calibration fluid (Where's closest?) Oz Reef Discussion 5 10-17-2008 9:46 AM


All times are GMT -5. The time now is 10:08 PM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2000 - 2015, Atlanta Reef Club, Inc.