is this a heat issue or nute burrn

This is my first grow socan you advise if this is neut burn or too much heat?

The picture below show all 4 issues i see.

This is an attic room and temp has reached 100f twice that i know of.

Temp now (f) 75 - 80 Day & 70 - 75 Night.
Humidity a steady 50 - 60%

Feed for last week = Canna A & B, Sensizime & superthrive.

Feed now = Canna A & B.

Still at 12 & 12 with light.

4 Weeks old!

Please advise

Could be both. I take it you don't know what EC is?

correct! What is it?

The curled up leaf edges are from heat. That's the plant basically trying to cool down when you see that.
The "bubbly" looking leaves are a nute issue. Your EC is another way of reading your PPM. If you know what that is, it could be an indication. Just offhand do you have a PH and PPM meter? If so post them, and people may be able to give you some more input with the right #'s ... as TheFaux said.. you have to get them, and post them so people will know what to help with.

Ok cheers for the advice.