Your soil will be fine unless you overdose it with non organic chemical fertilizers. The leaf you are showing looks to me like damage caused by the leaf hitting something like the edge of the pot while the fan is blowing on it. Really, nothing to stress about. As for great organic nutrients, personally, I can recommend and swear by "Bio-Vega" made by Bio-Canna for use during the grow/veg cycle, also some of the "Bio-Diesel" range put out by Sensi, such as "Super Natural".
"Flora Nova Bloom" one part nutrient is really good for flowering, especially when combined with the Sensi Bio-Diesel Bloom Booster or Bat Guano tonic.
Most of these are pretty strong, and half dilution rates works a treat. It is also much better for your plants to get two feedings of half strength, rather than just one feeding of full strength. Gently does it with cannabis. Your plants are living organic beings, not machines! Hope this helps... Organoman.