The large circular hay bales are pretty abundant and are fairly cheap in my area. There are also some coffee places like Starbucks that give out a good amount of coffee grounds on a first come first serve basis each day. I would like to buy one of these hay bales, mix in some coffee grounds, comfrey and a bit of compost from a previous pile to start making compost using the Rapid Composting method. I work at a nursery where we have a large digester that we put massive amounts of leaves into, and use pretty much just coffee grounds as the source of "greens"; but I am curious to know if there is any downside to doing this. Could the compost created be too acidic, or unbalanced in some way? Or are there any other foreseeable problems with this plan someone could warn me of?