General yellowing of plants

Yellowing of lower leaves , is usualy nitrogen toxcisity(ph too high). But Ive never seen it in a plant 3 weeks old. It is more likley heat stress. You said the leaves were droopy, are they kina twisty too? Did you start right off with the 400watt light or flora's. Check your temps durring the hottest part of the day.

^^^^^ nitrogen toxicity thats what i waz going to say. Damn well to clean the nitrogen out healthy piss is the best way to flush it out of this stage... Worked for me but then the flood rains came and fucked everything up -good luck

Piss? Dude, call me old fashion, but maybe you should just flush with water the ph you want it.I'm not knocking you, I've just never heard of that for nitrogen toc. Though i've had a few plants I wanted to piss on, prob not a good idea. It's all because the ph of the soil is to high. You want it around 6.5. It should clear up, but remember, every problem, or stress a plant goes through, affects your final weight. When I grow in soil I flush every 2 weeks, to rid the soil of salt build up, that causes the rise in ph. I toka toka toka