Small Holes and brown colour on leaves of young plants. please help!

Ok so my littlest guys have a brown smudgey colouring on the end of their leaves, and have tiny holes starting to form on the leaves. We’ve been getting some cold weather lately, i think this may have something to do with the problem so I changed the light to be on constantly in an attempt to keep the plants warm. I have 6 in total and only 2 seem to be having problems. apologies for the shotty photo but you can see what im talking about.


ILGM Support Tickett
What is the strain? unsure, seeds were just given to me by a friend
Size of space large room, light sitting roughly 40cm above plants
Soil or Hydro? Medium used? soil in pots. used a germinating soil from hardware shop, two plants planted 2weeks before the others are going strong
PH? unsure
Type of nutrients used? no nutrients yet
Temperature? warm on hand under light, now have it on 24hrs a day to keep plants warm outside temp between 8-16 C (I know this is quite cold)
Humidity %? 60% avg
400w metal halide
2 weeks old

Looks like something is eating the leaves. What do the under sides look like?

Just had a look and there are a bunch of tiny black dots on the bottom of the leaves, and I mean tiny, so small I can’t make out if you’re right and theyre bugs or just dots of dirt…