Alright, I've broached the subject of Pee Ponics in my Fishless Cycling Post.
Did you know that you can run a system indefinitely without fish?
I ran a Pee Ponics system for quite a while. It was my original Barrel Ponics system I built and cycled up fishlessly. Then I continued to run it fishless. I found that the pee ponics system needed about the same supplements as a system with fish.
Ok, I know many people get all grossed out by this, let me go into a little of the research I've done as to the safety of using urine as fertilizer. I learned that you can bottle and age the urine for a period of time until the pH goes up to 9 and the urea content has turned into ammonia. This has the effect of killing off many pathogens. I ran tests on e. coli which is on and in all of us and will get into urine from our skin even on a healthy person. So I tested fresh urine and fresh urine deliberately contaminated by fecal material. Both came up positive for fecal coliforms. Then I took samples of fresh urine and sealed it up and aged it till the pH got to 9 as well as taking a sample of fresh urine and again deliberately contaminating it then sealing it up till the pH got to 9. When both samples had the high pH I again tested them. Both came back negative for the fecal coliforms even though both samples when fresh tested positive. So this convinced me that my own urine when aged is not going to make me sick if I use it as fertilizer for a pee ponic system. I would suggest that one would not want to use the urine of some one who is sick nor would I suggest collecting the urine of non family members to use in your garden. When taking antibiotics, I would probably not save my urine for use in an aquaponics system and I don't think I would want to use the urine of anyone on especially toxic medications like chemotherapy. Otherwise, I don't really think saving urine to use as fertilizer is dangerous or even all that gross. I mean, do you know what happens to your urine when you flush it down a toilet? It is essentially getting sent back into the water supplies one way or another. Septic systems with leach fields simply leach the water back down into the ground water and hope that dilution will take care of the problems and sewage treatment facilities simply try and separate the solids from the liquids and add some chlorine before sending the water back to nature. If the flows are too high, they simply dump the excess that can't handle. There is no guarantee that sewage treatment will remove pathogens from the water.
Anyway, Pee Ponics does work for those who might need to keep a system running fishless for a long period of time and no, it doesn't require much pee unless you are talking a very large system. I'm fairly certain that most medium backyard scale systems could run on about one big pee a day.
There are still those who will be grossed out by this. To each their own. If one doesn't want to pee ponics, I certainly wouldn't force them just as I wouldn't insist on some one else doing Humanure Composting. I also wouldn't want to use all the pee for aquaponics since good hot humanure compost requires a fair bit of pee to keep in going really good.
I do highly recommend the Humanure Handbook even to people who wouldn't compost humanure, It taught me how to compost without having problems with stinking compost.