PLEASE HELP! leaf spotting. first grow.

I have 4 cream of the crop "purple paralysis" ladies in veg for 5 weeks. they're under a 600watt mh light in 3 gallon pots. I'm using about 70/30 coco to perlite mix and feeding with canna a/b, rhizotonic, cannazym and calmag at half stregnth cause I heard canna tries to rip you off with the amounts you should put in (please tell me if I should change that). Everythings been fine until now but few days ago I noticed one plant with some sort of damage on its leaf but they were a little thirsty so I thought that was the reason and didn't do anything. Now there is some degree of damage to at least a leaf or two on all four plants. I've been looking for bugs but haven't seen any, but I'm buying sm-90 in the next few days when ill be transplanting to 5 gallon.

They look fine as far as the NPK, maybe a little more cal/mag. And one of those looks like you splashed a little nute solution on the leaves. Just let it be. They seem a little big for transplanting but good luck.

If your pH is in range, i would start using cal/mag on all my plants. like once a month unless you have a problem
then increase the amount of times you use the cal/mag. until the problem clears up.
Your plants look a little to green IMO- watch how much (N) your giving them.

okay thank you so much!