Using the rubbermaid grow box

Any idea what I'm doing wrong? This is from 08/20 seedling. On 16/8 light cycle. Help!
5016169 Reviewed by 5016169 on . Yellow Leaf Edges - Potassium? Burning? Using the rubbermaid grow box Any idea what I'm doing wrong? This is from 08/20 seedling. On 16/8 light cycle. Help! Rating: 5