Foil is the best way for u to burn some holes in ur plants....it concentrates heat, creates hot spots the result its not good...try to get some flat white paint in ur grow area or mylar as soon as u can, but even if u cant do that right now, get rid of the foil...oh there is another nice solution, most stores sell what is called as Dual layered grow sheet u can consider that, its cheap and very effective...cya dude and keep i t up, its looking good