Usually a beginning sign of deficiency. But I think it could also be some sort of bug. Check your ph, maybe even calibrate your ph tester to be sure. What do you feed/ at what ph?
I'm new to growing.I have ph meter but don't trust it.New one will get here in a couple days.Im using FF trio.1/4tsp of Big bloom and Grow Big.There 29 days old.There planted FFOF and Happy Fog mixed 50/50
I got one a week ago and will say 20min you know it all. Its leaps and bounds better than the cheap ones which i also have. Sometimes the cheap ones are on, but are often off a half point or more.