just checked one and it has a 2 mm diameter circle of like black dots on the one lieaf not sure what it is and they seem to look like their getting a greyish color on al the leafs of all the plants cept the fresh ones.. im using random top soil left over from my outdoor grow i did in summer it worked for outdoor so why not in right? i used 20-20-20 plant prod. all purpose and only used 1ml of fert for 2.5 L of water and thats what happened as soon that i saw the bubbly type texture on the leafs i iimedeitly stoped giving it the nutes they look like say...a old man in a childs body if that makes sence. i only gave 2 tsp fo the nute mixture to them then skiped watering for 2 days or whatever..lights are (!) 42w cfl 6500k and (1) 26w cfl 2500k approx. 6 inchs off the planwt tops. in a sealed filing cabnet with a pc fan hooked up to a ac adaptor