First time hydroponic grower,bottom leaves are turning yellow,plant is super skunk,about a month old, has 4 sets of leaves, roots have not extended into dwc container yet pH is kept between 5.5 and 6.5. Using fox farm for hydroponic, grow box is 24 inches high, using led lighting, want to know how tall can I grow before I kick in blooming, I think grow box is 300 watt led, has filter and fan,light timer, have air pump, lites on 18 hours a day,if anything what I doing wrong, thank you,for any help