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calibration fluid for refractometer
- Thread starter Trio91
- Start date
Here's my refractometer recipe:
Make a 3.65 weight percent sodium chloride solution by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified fresh water. That amount roughly corresponds to ¼ cup (73.1 g) of Morton's Iodized Salt dissolved into 2 liters (2000 g) of water (giving very slightly more than 2 L of total volume).
For a rougher measurement in the absence of an accurate water volume or weight measurement:
1. Measure ¼ cup of Morton's Iodized Salt (about 73.1 g)
2. Add 1 teaspoon of salt (making about 79.3 gtotal salt)
3. Measure the full volume of a plastic 2-LCoke or Diet Coke bottle filled with purified fresh water (about 2104.4 g)
4. Dissolve the total salt (79.3 g) in the total water volume (2104 g) to make an approximately 3.65 weight percent solution of NaCl. The volume of this solution will be slightly larger than the Coke bottle, so dissolve it in another container.
Make a 3.65 weight percent sodium chloride solution by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified fresh water. That amount roughly corresponds to ¼ cup (73.1 g) of Morton's Iodized Salt dissolved into 2 liters (2000 g) of water (giving very slightly more than 2 L of total volume).
For a rougher measurement in the absence of an accurate water volume or weight measurement:
1. Measure ¼ cup of Morton's Iodized Salt (about 73.1 g)
2. Add 1 teaspoon of salt (making about 79.3 gtotal salt)
3. Measure the full volume of a plastic 2-LCoke or Diet Coke bottle filled with purified fresh water (about 2104.4 g)
4. Dissolve the total salt (79.3 g) in the total water volume (2104 g) to make an approximately 3.65 weight percent solution of NaCl. The volume of this solution will be slightly larger than the Coke bottle, so dissolve it in another container.
LOL......what does one do with over 2 liters of calibration fluid? I understand why Randy did the large volume....to increase the accuracy of the measurements of larger amounts....but 2 liters is a life-time supply for the entire NJRC membership!
Here's what I'd suggest. Visit a friends tank and ask if he/she uses a calibrated refractometer. Also ask what salinity they keep their tank at. When they are not looking, steal a small bottles-worth of water. As long as that water is kept in a sealed bottle, you now have calibration fluid. You could easily ask for a small sample, but stealing it adds suspense to what otherwise is rather boring subject.
I'll also throw in my two cents about using calibration fluid. By the way I have a 2 ounce bottle that I've had since 2007...and it's almost full. I rarely calibrate my refractometer....and let me tell you why.
1. I make 25 gallons of water and I know it takes 15 cups of salt, and a pinch, to get to 1.026 RI. If I mix the salt solution and my refractometer isn't very close to 1.026, I know I need to calibrate.
2. With every water change, I test the DT's water. If it's not 1.026, I re-calibrate.
Here's what I'd suggest. Visit a friends tank and ask if he/she uses a calibrated refractometer. Also ask what salinity they keep their tank at. When they are not looking, steal a small bottles-worth of water. As long as that water is kept in a sealed bottle, you now have calibration fluid. You could easily ask for a small sample, but stealing it adds suspense to what otherwise is rather boring subject.
I'll also throw in my two cents about using calibration fluid. By the way I have a 2 ounce bottle that I've had since 2007...and it's almost full. I rarely calibrate my refractometer....and let me tell you why.
1. I make 25 gallons of water and I know it takes 15 cups of salt, and a pinch, to get to 1.026 RI. If I mix the salt solution and my refractometer isn't very close to 1.026, I know I need to calibrate.
2. With every water change, I test the DT's water. If it's not 1.026, I re-calibrate.
This is great advice! I happen to know a member of the club who has a 2 ounce bottle of pure calibration fluid since 2007...and it's almost full.
using ro is not good, the calibration will be off at 35ppt. I did that and i thought i was running 1.025, i was actually running 1.022, coral were slowly dying. I would just get a small bottle of it, 6 bucks and lasts a long time, i calibrate mine weekly and i still have most of the bottle after a year.
Here is the home made calibration solution article:
http://reefkeeping.com/issues/2004-06/rhf/index.php
Here is the reason you don't want to use plain water to calibrate a device for measuring your SG:
http://reefkeeping.com/issues/2006-12/rhf/index.php#13
As mentioned in the article, you should use a calibration solution that is near the refractive index of the sample you will be testing.
http://reefkeeping.com/issues/2004-06/rhf/index.php
Here is the reason you don't want to use plain water to calibrate a device for measuring your SG:
http://reefkeeping.com/issues/2006-12/rhf/index.php#13
As mentioned in the article, you should use a calibration solution that is near the refractive index of the sample you will be testing.
