I've just give the plants their first feed of bio grow, the bottle recommends 2-4ml per litre i've gone for 1ml for the first dose, only gave them a little water maybe half a litre between the 5 of them because they're just recovering from my overwatering. I was gonna wait till tomorrow but I want to stop the yellowing before it gets worse. I can't see it being anything else really, just don't remember them wanting feeding so soon in previous grows, hope I've done the right thing we'll see.