Mary, I read an entire thread written by a guy on overgrow that used urine for his grow. That's all he used for the veg cycle. For the flower cycle he used urine and bloom nutes for extra safety. He only used the urine water every other time he watered. He was using a drip system with rockwool. It turns out the rock wool was acting like a pond filter and beneficial bacteria could live in there and protect the roots from the buildup of bad bacteria. So to make a long story short, dilute urine will work for dirt. Since the dirt acts as a filter. This will only work for hydro if you use lava rocks. Some said hydroton would work and others said there wasn't enough surface area. I've tried this using lava rocks in a swc container. It does work.