Don't panic, a first grow is a learning curve. Silica at 1 ml/l is normally harmless, so I doubt it's the main cause. At 6 weeks this auto is very small and pale, which points to a root zone problem: pH, overwatering or a pot that stays too wet. In coco/perlite keep runoff pH at 5.8-6.2 and water only when the pot feels light, with 10-20% runoff. Pale yellow-green leaves usually mean low nitrogen or a pH lockout, so start a gentle feed (about a quarter of the label dose) with pH 5.8-6.2 and raise it slowly. Don't top or stress her now, autos have a short life and she needs to keep going.