HAHA no trick question. I've been using the EI dosing method for the past 3 years which didn't say anything about MgS04 and the PPS Pro method does. Just trying to learn about the different fertilizing methods as I'm going to be switching over to the PPS Pro.
EI does in fact mention Mg and Ca as GH booster.
Not sure which version you read, but I never leave that one out.
I have not since I started helping folks in 1996.
So can I just add epsom salt to my solutions instead of purchasing the fertiliz
PPS is simply adding much less ferts, both add the same things, just at different rates. Some add a lot more PPS, then it's like EI, or they dose less EI, then it's leaner like PPS, but this is not exclusive to either methods, folks will add more/less to suit regardless, this does not define the method.
And from the article:
"SeaChem Equilibrium 1/8 teaspoon after water change." for a 20 Gal tank, this adds a nice mix of Ca and Mg.
If you want to adjust those individually, you certainly may, but I've found it only matters if the individual cations become limiting, eg, Liebig's Law applies in ALL cases. I've never seen a a confirmed Ca++ deficiency, not saying they cannot happen, just never seen one yet.
Mg++? Likely quite a bit, perhaps more than many think.
These I have seen.
Most just dose about 1 tsp per 60 gal of tank weekly, this resolves any K, Ca, Mg deficiency. Even at the highest rates of growth, this is plenty for all plants even if you have very soft tap water.
Hope this helps.