I've heard that fertilizers containing urea negatively affect the flavor of your final product. doesn't piss contain high levels of urea?
Yep, high in urea, but that's exactly why I use it.
Urine works great for plants like onions, garlic, or even basil, things you want to have a strong spicy, crunchy-sour flavor. Otherwise, I've never noticed it negatively affecting other veggies, but I only grow them in soil. I don't use it on flowering MJ, which I do hydro, but for a quick shot of completely free nitrogen during a veg phase it makes a nice supplement to an already pH buffered and nuted res. Well diluted and with plenty of aeration urine doesn't ferment, it breaks down like other organic teas do.
Let me put it this way, I only need to buy good and proper micro, blooming and fruiting nutes. And yes, I do regular res changes and clean my stones like many good bubble heads already do.