Optical refractometer brix % vs specific gravity

[ToledoTang]

I have a optical refractomer that shows the reading as a brix % at 20c. I also have 4 hydrometers that I've collected over the years that all have different readings: (I know these are not the best to use)

Instant Ocean 1 = 1.026
Instant Ocean 2 = 1.028
Coralife = 1.025
Coralife Deep six - 1.023

My refractomer is reading 4.4 brix %. I "calibrated" the refractometer with water and adjusted to 0. I used tap water instead of distilled water which I'm sure is not the best thing. Is RODI water any better?

Anyways, my question is, what is my specific gravity if my brix is 4.4%? is there a multiplier at all I need to use?

I looked online for a specific gravity to brix conversion table and the 4.4 says it has a 1.0175 SG.

My initial thought is that I need to properly calibrate the Refractometer and use the chart I found.

 

[kfisc]

I wish I knew what brix means, but tap water can very much give a false reading, always best to use RODI/distilled, or even better, a calibration fluid with a known SG (i.e. zero).

Swing arm hydrometers aren't the worst by a long shot- with those readings, and if you're keeping them rinsed so deposits don't form on the swing arm, your sg is fine.