The mg pre-nuted soil is a better bet. (if you can't or won't spend the money for all the better stuff you would need to run better soil)
Since you can't flush it to get clean smoke at the end of the grow you have to chop and stick the plant in a gallon of water and put it back under the light as if you had just flushed.
Trim the sides off that stalk too below the water line.
Clean smoke from pre-nuted soil.
If you learn to grow in mg pre-nuted soil and the tricks it takes you can do very well. I even use the stuff believe it or not. It's just too cheap and easy... And I like cheap and easy like Amy Winehouse likes crack.
But boy did I hate the stuff when I tried using it like normal potting mix in the beginning.
Don't add fert this time and you won't have to flush which doesn't work and it won't throw off the ph and you won't have all the problems you did before.