Magnesium - First time dosing!

[Protodad]

So I’ll start out by saying I have never dosed anything over my 15 (on and off) years of reefing. Finally trying to do a tank right and this was my next step. Ended up getting a brs 2 part system.
my tank is currently about 25g and very lightly stocked. First set of readings were:

Calcium - 460
Alkalinity - 8.4
Magnesium - 1200

Calcium was high so I left it alone. Dosed a bit for alk to get to 9.0 based on the BRS calculator.
Now for mag, I’m confused. The instructions say pour in a bunch after burning through the two bottles. The calculator says to add 10oz to bring it up to 1350 but not more than 100ppm a day.

But my magnesium is really low. Should I just add 10oz now and try to “baseline” my magnesium back to 1350? Or should I leave it alone and wait (a long time) to burn through two bottles?

 

[Biglew11]

I'd do 5 ounces today then 5 ounces tomorrow. It would raise it slightly more than 100ppm but will be fine. The 100 ppm at a time is more of a concern with adding impurities to the tank. Low magnesium can allow alkalinity and calcium to precipitate out of solution. It is used by organisms but at a very slow rate, that's why they tell you you can dose it after you've dosed a couple bottles.