Bump! I'm interested too. I started dosing two part B-Ionic a few months ago and my Mg drifted to 1260. So I figured I'd do a few extra water changes to bring it up. Out of curiosity I checked the freshly mixed Oceanic and it was 1245 with Salifert or 1300 with Red Sea. That's no way to bring it to my target 1310 - 1350 range. BTW, what level do you shoot for?
Big whorls have little whorls, Which feed on their velocity;
And little whorls have lesser whorls, And so on to viscosity
Lewis Richardson in 1922