I have 10 plants going, 3 different strains in a 4x4 with 600 watt bar led, grown in coco&perlite. Feeding advanced nutrients base and power si. They're at 3 weeks and growing really well except 2 that are same strain. They have yellow edges and tips but the tips get soft a thin. To me it looks like a virus or something different going on. Any insight is appreciated. Thanks