Braune Flecken an den Blättern

Hey there, so there are many causes that could be leading to your problem. My guess is point 1 because of point 3. 1 Nutrient deficiency: A lack of calcium, magnesium, or potassium can lead to brown spots. Calcium deficiency often shows up as dark brown spots on the leaf edges. 2 Overwatering: Too much water can damage the roots and cause brown spots on the leaves. Environmental conditions: High humidity and fluctuating temperatures can also lead to brown spots. 3 To rule out over-fertilization is relatively simple by measuring the pH of your runoff; if it's above 6.5 or below 5.7, then something is already off. If the value is outside this range, your plant goes into a nutrient lockout and can't absorb various nutrients, leading to deficiency signs. The EC value should also not exceed 2, otherwise, you have too many salts in the soil. In your case, I suspect one of the deficiencies mentioned above, because even if you add CalMag and potassium, if your pH isn't right, the plant won't absorb them.