Epsom salt question

Epsom salt i think it is called, is used to fix a mg and cal problem,how long will it last for? i have a tank 100L and was thinking about filling it up with 90L and leaving the cycle on if i mix in the right amount of salt at the start (when i put the 90L in) will it be throughout the whole feeding of that 90L or will it be a problem? would having 2 tanks and 1 empty till feed time and the other full so that it gets pumped into new tank and mixed a bit? really high

I mix 1tsp of epsom salt per gallon of PH'd water during a flush. The salt helps to leach out the deposit byproducts of fertilizers you're using. I don't believe salts are an adequate solution to cal and mg deficiency...They contain on trace amounts.

mgso4............how does that fix calcium? dolomite lime fixes mag and calcium

what shalli use then becuase the yellowing and browning on my plants anoying

let's see................