🔎 Symptom Analysis:
1. Image 1: The bright, jagged lines and spots look very typical for thrips infestation or leaf miners. It seems like something has "dug" through the upper cell layers.
2. Image 2: The irregular, pale discolorations with a silvery sheen and yellowish spots strongly indicate sucking symptoms from pests – typically thrips as well.
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🐛 Possible Cause: Thrips
Tiny, elongated insects (1–2 mm) that often hide on the undersides of leaves.
They suck out plant cells, leaving silvery pale green spots.
The characteristic lines are from their "movements" on the leaf surface.
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Secondary Cause: pH Level & Nutrient Availability
An incorrect pH level (outside 5.8–6.5 in the substrate) can:
Cause micronutrient deficiencies like magnesium, calcium, manganese.
The symptoms sometimes resemble pest damage.
Combined problems are possible: A pH issue weakens the plant and makes it more susceptible to thrips & co.
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✅ Recommended Steps:
🔬 Inspection
Examine the undersides of the leaves with a magnifying glass for small, quickly moving thrips.
Check if you find black specks (thrips droppings).
Treatment for Thrips
1. Neem oil (3–5 ml/L, emulsified with mild soapy water) – every 3 days for 1–2 weeks.
2. Predatory mites (e.g., Amblyseius cucumeris) – biological solution.
3. Leaf shower with water + a few drops of potassium soap (not on flowers!).
4. Remove the most affected leaves.
📏 Check pH & EC
Measure drainage pH and, if necessary, the pH of your watering solution.
Goal: pH 6.0 ± 0.2 in the substrate.
For Biobizz soil, lower pH with citric acid or vinegar if too high (you mentioned the substrate buffers to pH 8).
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📌 Conclusion:
Very likely thrips, with possible pH stress as a trigger.
You should combine pest treatment + pH correction.
After that, the new leaves should grow healthy.
If you give me the pH and EC values of your solution and drainage, I can suggest a targeted correction.