another ? i just went and checked them and all are doin great. and startin to thickin up but 1 on it's lower leafs are wilting. and i noticed a white powder on them and on the clay balls. im guessing this is cal build up as i have seen it on sum of the clay balls that i have washed off b4. is there something i can do about this? i tried to wash it off but when it dried it was still there.is this something to worry about? i need to change the nutes i think i have'nt changed it going on 3 weeks now.i have just been topping off with ph'd water.any suggestions?