Refractometer calibration

75gal

New member
Is it possible for my Refractometer to be off despite being calibrated with the calibration fluid? When I test my mixed salt for magnesium it's significantly lower than the advertised amount. (Using Red Sea coral pro ) I'm just not sure if it's advertising at work or if I'm testing wrong. Thanks
 
how old is the calibration fluid? if ever left open for a period of time and evaporated in the bottle, then it would for sure be off.

but otherwise, if the calibration fluid is accurate then it is likely the refractometer is reading accurate post-calibration.

i'm not following your concern about this relating to magnesium though?
 
I was to understand that the salinity helps hold magnesium in the water. If salinity was off then Mg would be off too. It says right on the bucket...30.6ppt = 1185-1245mg. 33ppt = 1280-1340mg. 33ppt = 1360-1420mg.
 
If the refracteter is off then yes it could effect your levels. But I would not trust any of the advertised levels on the side of the bucket. From every batch of salt to every bucket, can be different. I usually test every new box of salt just to get a general idea of the levels, but always make my adjustments off my tank parameters.
 
For short term grab some distilled water and calibrate to zero till you have access to new test fluid, I have been using reef crystals, and I am having serious trouble getting my mag,alk,and calc balanced lol
 
If the refracteter is off then yes it could effect your levels. But I would not trust any of the advertised levels on the side of the bucket. From every batch of salt to every bucket, can be different. I usually test every new box of salt just to get a general idea of the levels, but always make my adjustments off my tank parameters.

^^^this

for instance, i have always used Coralife Salt, mainly because of its high Magnesium levels. I would always get 1400+ from it. I just used an entire two boxes of Coralife salt when redoing my tank and Magnesium only measured at 1200ppm, while Calcium measured much higher than normal.

you just have to measure periodically and adjust as-needed when it comes to certain parameters.
 
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