Mag dosing affecting my refractometer reading.

[Hal]

When I mix up 40 gallons of new saltwater to 1.025 I've started to add 20 oz (2.5 cups) of Randy's magnesium supplement (7.5 cups mag sulfate, a.k.a. epsom salt, with 2.5 cups mag chloride in 1 gallon of RO water). This boosts the refractometer reading to 1.028 or higher. Is this a problem? My tank is now reading 1.028 on the refractometer.

[Randy Holmes-Farley]

I think that must be an error of some sort. Boosting magnesium by 100 ppm with most additives will raise salinity by about 0.4 ppt, or from 1.026 to 1.0263. :)