Hello. DWC system. Some kind of deficiency symptom...

Hey Buddy DWC – Lower Leaf Damage: What’s Actually Going On 😇 Short answer: This looks like a magnesium deficiency + early calcium uptake issues, driven mainly by water temperature and uptake speed, not by lack of nutrients in the solution. You’re feeding enough — the plant just isn’t using it efficiently yet. ⸻ 🔍 Why I say this What the leaves show: • Damage starts on lower / older leaves • Interveinal fading and patchy discoloration • Some dry, necrotic-looking spots • New growth looks mostly healthy This pattern does not match nitrogen deficiency or nutrient burn. ⸻ Let’s look at your numbers (they help a lot) • pH: 5.8 ✅ (good) • EC: 1.3 ✅ (reasonable for this stage) • CalMag added: yes 👍 • VPD: 1.3 ✅ • Water temp: 25°C ⚠️ That last one matters more than people think. ⸻ 🌡️ The real culprit: root-zone temperature At 25°C, DWC roots: • absorb oxygen less efficiently • become more sensitive to Ca & Mg uptake issues • can show deficiency symptoms even when nutrients are present This is a functional deficiency, not a feeding mistake. ⸻ 🧠 Why it shows on lower leaves first Calcium and magnesium are not very mobile. When uptake is limited: • the plant prioritizes new growth • older leaves show damage first • symptoms appear “random” or blotchy Exactly what your photos show. ⸻ 🚫 What this is NOT Let’s clear that up: • ❌ Not potassium deficiency • ❌ Not nitrogen deficiency • ❌ Not nutrient burn • ❌ Not pH lockout So no flushing, no drastic changes. ⸻ ✅ What I’d do next (simple & safe) 1️⃣ Lower water temperature if possible Ideal range: • 18–22°C Even dropping 1–2°C helps a lot. ⸻ 2️⃣ Keep CalMag — don’t increase much You already added it correctly. • Keep the same dose • Don’t chase the damage • Watch new growth, not old leaves Old damage will not heal — that’s normal. ⸻ 3️⃣ Hold EC steady for now • 1.3 EC is fine • Let the plant stabilize • Increasing EC now would only add stress ⸻ 👀 What to watch over the next few days • New leaves should stay solid green • No new spotting on fresh growth • Roots should stay white / healthy • Overall posture should remain upright If new growth is clean → you’ve solved it. ⸻ 🌱 Final takeaway This is a classic early DWC Ca/Mg uptake issue, made visible by warm water. Your setup is good. Your feeding is reasonable. This is about fine-tuning, not fixing mistakes. Growers Love my friend hope this helps and remember this is just my humble opinion, please follow your instinct 🙏👊🙌

Your reservoir temperature is quite high, be mindful that it's a breeding ground for all sorts of pathogens that can affect how your plant looks like above the water level Have you checked what is the condition of your roots? Look for any browning, slime, weird smell I would not worry about the first leaves they usually throw a spectrum of weird traits and problems Most important is to look at the overall growth and condition of the whole plant

Looks like mechanical damage from hitting the plastic lid.........no doubt at night when the leaves are lowered and the fan blows on them. Does not look like a nutrition issue to me, otherwise more leaves would be affected.

Cal mag deficiency from too intense light Adding more Cal Mag won’t fix the problem. Backup your light or lower the intensity.