This happened at two weeks with my aerogaden what should I do ?
you need to give specifics, this isn't a guessing game. What is the ph, ppm's of your water, what temp, what nutes and in what amounts. What system are you using flood and drain, dwc...This happened a day after changing the water and just using two extra cfl lights. maybe to much water?
bottled water might help, changing the rez every week will help, maybe investing in real nutes could help, like gh floranova grow is very simple to use, just add amount/water and it will lower the ph on its own. how do the roots look? are the brown and slimy?