This just a simple case of watering too often pal. Are you watering everyday yeah? It looks like it. As your plants are healthy, PH is fine. Leafs are a little too green but not shiny so cut back on the N. And let her fully dry out for 3 days at least and water every 2-3 days. With them containers once they get wet they keep the soil damp for ages so even less of a need for waterings is called for. Also are you letting them sit in any run-off it's Just too much water too often. She looks healthy overall. Good luck.