20 gallon bucket... thats huge... i wouldnt be able to fit more than 9, unless i went with 3-6 20 gallon and the rest 5 gallon(some 10-20)

Another problem i am anticipation an i am not quite sure how im going to make it work... i have a veg room and a flower room. but im worried that the different heights of the plant or going to be so varient that either the younger ones are too far from the light and may stretch or i lower the lamp and the almost mature ones are going to get burnt. is this problem i will face...al though an idea just came that i can prop up the smaller one to match the big ones. ideal? and if i remember correctley from top node to bottom of lamp 18-24 inches.. will that same distance work for the my 400w mh in veg. on 24/0 .