its in between 41/4- 41/2 inches at the base. My thinking is that I would want to leave enough room for growth so I wouldnt be one of the guys that says shit, I need a bigger tube. But I also wouldnt want to get to big of one and hinder my results. I might just get a tube from a place like that so I dont have to go and buy 25 ft of tubing, a gravel cleaner and a quick disconnect. Even though I will probably end up buying that stuff anyway.
gprent, can you help me with a list of parts and possibly pics. Im totally new to this and I would like to get a complete understanding of what im getting myself into. If you cant get the pics, thats cool. Thanks for you help.