what is so special about a colema board? can I just lay on a board the size of my body over a bucket and attach a tube with a tip to a bucket and use an enema laying flat on a homemade board? is there anything special about a colema board that you bought? what is different besides the amount of water in the bag, because I can pour about 1/2 gallon in mine? how much do you need fo fill the entire bowel?