your initial pics where a P deficiency, you are most likely using too little or imbalanced nutes. The pics look like fig. 13 and 14 here
http://www.drugs-forum.com/growfaq/97.htm . Nute burn is a flat crispy look to the ends of the leaf, like fig 4 in the above link. it is my opinion that most people use imbalanced nutrients and that is not helped by constant flushing due to misdiagnosis and low nutrient dosages because the grower chooses to err on the side of caution.
glad to see the foil gone, and the temps down. it would help to know what make and model of nutes you are using, your rez size (you probably already said but my mind is on a roll), and the ml/l of all additives and base nutes and EC readings, and also the age in days.
if you want to post that all in a concise post, I will tell you if I see anything wrong.