OohFeeshy
It's only forever; not long at all...
To quote-
Don't pee in your tank!
Don't laugh, some people are saying this is a good way to provide ammonia for a fishless cycle.
Human pee isn't the same as what's produced by fish. Urea is whats produced by humans and it is a modified from ammonia (NH3) to contain 2 nitrogenous groups, and is basically non toxic. Also, its somewhat more concentrated than ammonia from fish, as they need to release large quantitites of water to maintain osmotic balance.