need help on the seedlings. 2.5 weeks old. unknown strain under 400mh. ive notice the new growth is a lighter green than the rest and the tips are yellowing.. i havent fed it any nutes but added liquid karma and ph 5.8. is it time for nutes?how much should i start out with? http://forum.grasscity.com/grow-room-design-setup/460514-new-cab-400-mh-hps-scrog-dwc.html