2 PLANTS ,2 1/2 FT TALL , 400W HPS , PH @ 5.9 , SUFFICENT VENTILATION , ROOM TEMP @ 75 DEG. ,, JUST WENT TO 12/12 4 DAYS AGO, SWITCHED BUD NUTRIENTS, . HAD ABOUT 15 LEAVES FALL OFF TODAY, CHECKED PPM'S AND THEY WERE @ 1920ppm, any suggestions !! thanks:confused: