MSU R/O - Do I need add'l MgSO4?

[D_novice]

Greetings, I use MSU rain/city water formula (with either rain or city water, depending on the time of the year). I use 1/2 tspn gallon in the growing months to get a TDS of about 300. I also do water leaches, and sometimes do Ca Nitrate, Seaweed Extract, or Pro-Tekt silicon formula instead of MSU. I have a pretty varied collection: Paphs, Phrags, Oncdm alliance, Cymbidium, Catt, Encyclia, Laelia anceps, a handful of Phals and AU Dens.

That formula is 2% Mg and 10% Ca.

Do you think I need additional epsom salts? I was hoping that making MSU my regular formula would mean I could skip that.


My water specs: 7.0-7.2 pH, 90-ish ppm TDS, .14 mS EC, and 60 PPM alkalinity. (First 3 measurements with Milwaukee Instruments 802 meter, alkalinity with LaMotte kit. Have to double check the alkalinity, wouldn't swear I was using the test properly when I checked that.)