This was a great idea by @MrPeat. This is pics for deficiencies/excess of nutrients that you have experienced. Nutrient issues aren’t just a matter of, “I underfed” or “I overfed”. There’s a lot of things in motion that can cause different things.
What have you run into? What did you find the root cause and what was the resolution?
Calcium deficiency. Caused by running distilled water. Switching to tap water resolved issue.
Phosphorus deficiency. Caused by soil ph dropping to 5.8. Flushing with 7.0 water brought ph up to 6.6 and resolved issue
Iron deficiency. Cause by a water conditioner I was using to dechlorinate the water. Spraying with clamag foliar spray and discontinuing using the conditioner resolved issue
This will likely turn into a “what’s wrong with this or that leaf” thread, but I hope not. This is a post your deficiency/excess thread and how you resolved the issue.