I use fox farm forest ocean soil, I barely used any nutrients so far, it was growing fine, I add bioRoot 0-1-1 with each watering though and just regular lemon 🍋 to lower the ph.
The lower leaves could be from the leaves touching the soil when the plant is in rest mode, or from water getting on it from watering. It could even be start of a calcium deficiency. Make sure when you water you get run off out the bottom of the pot. Make sure your ph is in range. Don't weed with every watering try and feed every 2nd or 3rd watering. Wait for top inch of soil to dry inbetween watering/feeding.