ok ok hmmmm well I personaly keep my humidity around 65 to 70% during veg growth during flowering i drop it to around 30,ok im glad to hear that you dont add any other nutes lol i just looked up an artical that mentioned a mg def that caused the leaves to curl downward like that so grab some cal mag plus its ganna hit for around 17 bucks at your local hydro shop you should see results in about 3 days if that doesnt help we will take it from there buddy well take care hope the cal mag helps the issue...