Help on new girls

Hi all
Ive been at this for a few years now and everything thing has always gone relatively well. I’ve just started my latest ones … super silver haze. Well they’re 10 days old.
They’ve been in the bubblers now 4-5 days. I noticed a couple had some dark spotting and problem indicators on the new leaves.
Ph is 5.8
Ppm is only 350 … roots were only just starting to hit the water so i hadnt pushed the ppm up.
Nutrient temp 70-71f / 21c
Plenty of air in buckets
Room temp 24c/75f
Humidity is down at the moment im just sorting it out but it goes between 55-65%.

I was thinking calcium deficiency? ?? Any ideas would be appreciated.

Sorry having difficulty working this out … wasnt ready to post.