Actually in coco I use a kabob  Skewer and it works pretty good most of the time. I am going to do that on the outside plants too this weekend. They are 2 lb bags and I have dowels I can use to aerate with.  I dont worry about cutting roots, they grow back a double like topping. If I have one plant growing a little slow in Hydro I will give it a root trim and Bam its the leader of the pack.