Quote:
Originally Posted by MitchM
Lojack, how did your refractometer drifting out of calibration cause your salinity to drop?
When you did water changes, did you add less salt to each batch?
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I don't weigh or measure my salt. I have two 80 Gallon Drums, one for fresh RO, and one for Saltwater.
My RO unit fills the freshwater drum and runs off of a float, and it's connected to the drum I use for saltwater, I open the valve and fill the other. I just add salt to the drum, and test the salinity to get it where I want it. Weighing and mixing a set amount of salt with a set amount of water is inconsistent because the batches of salt are rarely on spec and exactly the same.
I was calibrating my refractometer with Distilled water as per the instructions that came with it, then I stumbled across a really good article that was talking about how distilled water and RO water for calibration can cause refractometers to drift. So I bought some Calibration solution that is exactly set to 1.026 concentration and found that my Refractometer was indeed off, by .008 which is fairly substantial in the grand scheme of things.
I intend to add a conductivity probe to my Apex to prevent this problem in the future ... however right now I'm still checking salinity the old fashioned way.