Checking calibration on my refractometer....

So, I was reading thru sailorguys' thread on this very subject:
http://www.3reef.com/forums/general-reef-topics/calibrating-refractometer-151938.html

rather than tangent on his thread, I started this one referencing his and the link rayjay provided
Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com

I read the entire link, and decided the author thought it was easy enough and gave household ways to make your own calibration fluids.
The fluids are slightly different for what you're calibrating, so I made up a batch no his calibration fluid for refractometers.

I've been using a refractometer since Labor Day 2013, don't have any store bought fluid and at first used my 0TDS RO/DI @ 0.
Then a friend brought over some, and we calibrated it, it was off a hair and I reset the set screw for the fluid.

Fast forward until today- I/we don't drink any soft drinks, but I was lucky enough to have an already opened/flat 2L Pepsi bottle in my fridge.
I prepared the solution per the directions for calibration fluid in the article.

At first, it was off by about .002-.003!
So I warmed the solution on the stove so it was about like my DT water temp and rechecked many times.
**I realized long ago that you have to clean the instrument AND the eyedropper with RO/DI after each trial - or you WILL get inaccurate results!

After warming my RO/DI/prepared S=35 solution and rechecking- it was less than .001 off from the last time I used the calibration fluid- which can also be off some!

All in all, I left the set screw where it was, and will continue where it is now- I think it's close enough.

I'll re-do this test soon, and borrow or buy some cal. fluid

Thanks to sailorguy for getting my to check this as a result of reading his thread.

 

Cool Todd.Now that you know the answer to that question maybe you could help answer this one.

mutton chops or goatee - YouTube