2 of my 4 plants, all about 4 weeks old, have their bottom rounded pedal looking leaves withered away with a yellow color and practically fallen off. one which is in miracl grow moisture control soil with perlite and the other with natural brown soil from my outdoor garden(mixture of some perlite cow maneur and others i do not know of). i water them every other day, or when dry to the touch, with mild temp tap water. they are placed 24inches from my 400watt 53k lumen hps light. i have a fan constantly breezing over the light and plants. (in closet) for ventilation i leave the door opened all day and have a window fan in the bedroom blowing in air from outside. the temp is constantly 75-80F. is this a big problem? will my plants still continue to grow. the regular leaves are healthy looking.