Please help on leafs on top wilting and some discoloration

Inert substrate 50% perlite 50% sphagnum peat Temperatures between 21 to 28c always w AC connected to the air fan in. 400w hps cooltube 30-40 cm light distance Always let the substrate dry before watering every 2 days - 1,5 l per plant - always 20% runoff 11l pot I have never measured PH, I am using mineral water ph 6.4 Using biobizz Fiah mix , Grow , bloom and top max No calmag ... Flowering using grow 1ml week, bloom 4ml and top max 4ml on every water ( could be a lot ) I will change to bloom and top max 4ml then water water water Add calmag

is it hot? too close to light? curling in on itself is a sign of conserving water. Could be over-nuted too. assuming soil -- do you let top 1" dry before watering? do you also ensure 20% runoff to waste while watering? if not, start doing these things, first. Also, get pH in order for you rsubstrate. if soil - 6.5-6.8 of anything that goes into it... even test soil if you can. In general soil can correct some amount of pH on its own, but better to avoid that "maybe". Get that stuff in order, if it continues, you can make a better decision at that point... if you already do that stuff, reference a leaf chart and consider what you have fed over the last 4-6 weeks. If the leaft chart tells you "Ca deficiency" but you provide plenty of ppm of Ca, it's not Ca... it's lockout caused by something else.

The trick on the inlet fan is optional but suggested like calmag , it does not affect so much but it wilk help 😊 unless your outdoor air is very cold like under 15c

I m feeding rigth now w biobizz bloom 4ml and top max 2 ml per L, every 2 days with water only between. Bio grow 1ml once a week

My air inlet connected in a AC is blowing direct in the plant pot, could be the cold affecting its flowering?

You are giving too much N , the buds down discolored is because it don’t have enought light, try to remove some leaves to get a better penetration on all the buds ✌️🏽