need help asap.i have 10 ak 48 about 20 days and have problems.all 10 have yellow leaves and start from bottom to top , and their turn black , some of them from top of the leavs and other from the midle. i have for neaw 1 hps 250w. soil made by me 2/3 peat moss ph 6,4- 6,9 and 1/3 perlite...