Brown spots on the leaves w8

Calcium deficiency. Remember too, what is showing in the leaves now, is a direct reflection of what was happening in the root zone 2-3 weeks ago. I would say this problem has been manifesting itself for 3-5 weeks already, it is quite advanced. Adding a Cal/Mag supplement to your feeding schedule or upping the dosage if you are already using one will help. The damaged leaves will not recover, but it will slow it from getting worse and eventually stop once the plant is getting adequate calcium again. You can be quite generous with the remedial dosages (double strength), it is hard to over dose with cal/mag, but settle back down to normal dosage recommendations once yiou start seeing improvements in the plant.

This is the effects of no calcium uptake. Which probably is the result of an imbalance of pH of your soul. I suggest a flush of your media with a pH of 6.3 water. Then every watering pH to 6.3 and apply enough water where roughly 20% will come out of the bottom of the pot. This will wash away any excess salts and keep your pH in balance. I hope this helps.

I reviewed your diary and I see that you are adding calcium to your diet; the spots are symptoms of calcium deficiency. The pH of your watering might be off, and that's why you aren't assimilating the calcium. Keep the pH between 6 and 6.8 for better nutrient absorption.