I have 4 plants that are 20 days old and and I started them in Foxfarm ocean forest soil and they have been looking good and now I have noticed last night that the set of round leaves are turning yellow and the first true two leaves are slightly turning yellow, not much yet, but I can tell. There are also like 4 sets of leaves on them now. Could this be the beginning stages of nitrogen def? The guy at the hydro shop told me the soil has enough nutes in it for a month, but it has only been 20 days. Could the plants of almost used all the nutes in the soil already? I have them in 16 oz. dixie cups. I just watered them last night so I cannot water them for another 3-4 days, so if they turn yellow on the bottom leaves somemore, should I give them 1/4 strength nutes in like 3 days after the soil dries up? Thanks One of the plants it looks like the veins between the leaves are alittle purple too.