4th week of flower organic amendments in coco ph 6...

hello my friend In my opinion your problem must come from: 1. Diagnosis: Calcium (Ca) and Magnesium (Mg) deficiency ​The small yellow and brown spots that appear on the upper leaves are typical of a Calcium deficiency, often accompanied by a lack of Magnesium. ​2. (The “Why”)? ​There are two probable causes here, despite your amendments: ​Coconut substrate: Coconut fiber is known to “trap” Calcium and Magnesium. Even if you added some with gypsum and rock dust, these elements take time to decompose and become available to the plant organically. ​The pH at 6.5: For coconut, 6.5 is a little too high. In coconut, Calcium and Magnesium are better absorbed around 5.8 - 6.2. At 6.5, you are at the high limit, which slows down their absorption. ​Peak Demand: Week 4 of flowering is when the plant demands the most Cal-Mag to build bud structure. ​3. How to act quickly? ​Since it spreads quickly, you can't wait for your solid amendments to break down. ​Immediate solution (The "Quick Fix"): Use a liquid Cal-Mag supplement (chelated if possible) during your next watering. This will be instantly available to the plant. ​Adjust the pH: Try to lower your watering pH to around 6.0 - 6.2. This will help the plant to unlock the Calcium already present in the coconut. ​Check watering: Coconut should never dry out completely, especially with organic amendments. Always keep it moist (like a wrung out sponge) so that microbial life can work on your “top dress”. ​In summary: It's not that you didn't put enough nutrients, it's that they are not available quickly enough for the plant because of the support (coconut) and the pH. Rapid fluid intake should halt progression. I hope I was able to help you have a nice day my friend