Create Salinity Calibration Solution

[Mikeltee]

I bought 2 different calibration solutions and one reads 1.025 and the other reads 1.028. I want to create my own for s35. After reading Dr Randy's assumed old writeup:

https://reefkeeping.com/issues/2004-06/rhf/index.php
I do believe that I need 6.2g of iodized salt to 161.0g of distilled water to reach a salinity of 1.0264 @20C. I am wanting to verify and then offset a Milwaukee digital refractometer which does temp compensation so I assume the temp doesn't matter. It's the older green one and has served me well for a few years at making saltwater with a reading of 1.027 on the meter.

Is this correct?

 

[Gtinnel]

For a refractometer standard solution I’ve always used Randy’s recipe of 3.65g of salt to 96.35ml of water. That gives the 3.65% that you’re trying to get. Your measurements gives 3.71% which I don’t believe is correct for the standard for a refractometer. That or I’ve been making it wrong.

Also, I don’t have anyway to measure weight that accurately so I scale mine up 10x and mix 36.5g of salt to 963.5ml of water. The more you scale it up the less a small measuring difference makes.

 

[Gtinnel]

Here is a thread where Randy gives the recipe for a refractometer (post #9)
https://www.reef2reef.com/threads/ma877-milwauke-salinity.989442/#post-11448814

 

[KStatefan]

The 6.2g of iodized salt to 161.0g is for a hydrometer.

You need the one for a refractometer. Your meter might be giving you a specific gravity number but it is measuring the refraction of light. You need to use the one Gtinnel posted above.

 

[Mikeltee]

Shes dead nuts!

 

[Gtinnel]

I use the same Milwaukee MA887 and love the thing. I honestly haven’t even calibrated mine in years, I just periodically check it with the diy test solution and it’s always been accurate.

 

[Mikeltee]

I use the same Milwaukee MA887 and love the thing. I honestly haven’t even calibrated mine in years, I just periodically check it with the diy test solution and it’s always been accurate.

I keep a bottle of distilled water and calibrate every use because I use the same bottle to rinse it.

 

[jda]

This probably does not help many, but at 50g bag of IO in a 44g brute filled just to the top is 1.026 on the money.