when the sides of the leaf curl in half and the leaf bends downward in a claw it is a direct result of over doing nutes. Let em dry out pretty good , then use straight ph'd water for the next couple feedings after dried. Do not follow the directions on any of those food containers, 5ml food per liter of water is tooooo muchy.
I use like 5ml per gallon of water. I've had similar problems in the past with that. For 120 litres of water i use 5 scoops(Table spoons) or (21 ml scoop) absolute maximum. Remember that ph is adversley affected by TDS. Total dissolved solids are high then ph will be low...and vice versa
In veg state use a 30-10-10 food ok, in flower use 15-52-15. Every second feeding should be straight ph'd water too. okely dokely, and burn a torch a coupla times a day in there(of course when lights are on), plumbers torch with coleman camping propane cylinders. 4x8 room for two minutes, 3 times a night three hours apart.