I suppose that would be one way to do it. I think that is very dumb though. The biggest issue is all the chemicals you would also add to your tank. If you're a smoker like myself, then all those bad chemicals you get from smoking exit your body through your urine. If you're a unhealthy eater, then it's the same thing. Granted one of the big reason you use the bathroom is to get the ammonia out of your system, another reason is to get all the chemicals you ingest out as well. It's much safer in the long run to buy the ammonia, or use shrimp.