Did 3ml/L cause overfeed, rust spots & clawing?

Hey, I'm going to try to help you. The Diagnosis: Overdose followed by a lockout Burnt tips: This is a nutrient burn (too much nitrogen/salts). Advanced Nutrients is very concentrated, and 3 ml/L for an auto in week 3 is huge. Rust spots: This isn't necessarily a lack of Calcium/Magnesium, but probably a lockout. The excess salts in the soil have dropped the pH or saturated the roots, preventing the plant from absorbing CalMag, even if you're giving it. Yellowing at the bottom: The plant is drawing from its mobile reserves (Nitrogen) to try to survive at the top, or the roots are suffering from the accumulated salt surplus. 2. What to do immediately Do not add CalMag or fertilizers to "correct" the spots, you will worsen the lockout. Check your pH: This is the most important. If you're in soil, your watering water should be between 6.0 and 6.5. If the pH is off, the plant no longer "sees" the nutrients. Next watering: Continue with plain water (adjusted pH) but with slight drainage (about 10-20% of the water should come out of the pot) to flush out the accumulated salts. Drastic reduction: When you resume fertilizers (not before the yellowing stabilizes), never exceed 1 ml/L or 1.5 ml/L. Official programs are often designed for massive plants under ultra-powerful lights. 3. Visual analysis (your photos) You can clearly see in photo 2 the typical "rust" spots of a Calcium problem. But since you're giving it (0.3 ml/L), it's proof that it's an absorption issue (too much Potassium or too low pH) and not a real deficiency.. I hope I was able to help you, have a good evening.