Here is what I call the "Real Meat & Potatoes" part of the V-Tower. Medium density (green) Matala brand Koi Pond Filter Media, available from Amazon and many other sources. See www.matalausa.com for more information, and you will soon understand why this is the absolute best fiber media for any vertical grow tower. I prefer to use two sets of strips that are 20" long and 3" from front to back. Sandwiched together, this gives you two 3x3x20 inch sections of grow media that you can easily slip into the V-Tower body from each end with no need for a special pulling tool.This design also makes partial replanting of the tower much easier. Simply follow the manufacturer's instructions for cutting the media and choose whichever method you like best. Personally, I prefer using their reverse table saw method.