I use el cheapo laundry detergent from Canadian Tire. In fact, I keep a jug mixed about 20 to 1 (definitely not a precise measure!) in the bathroom and pour some (maybe a couple of cups) in the toilet each time after flushing. That water sits until the next use. If you watch, a good sized jug can be had for $2 or less. Never have any smell, plus I would suspect the soap slopping around doesn't hurt. After dumping, I dump a whole (mixed) jug in.