The only problem with reading Diana Walstad's material is how involved it can quickly get and it is far riskier than my method, which by the way I have used in setting up dozens of tanks. I do not recommend Walstad for anyone not well versed in more simple methods. Using soil is fraught with complications if you don't know exactly what you are doing.

I agree with lightly stocking, and sufficient plants. But it does work. Ammonia and nitrite will be zero, and it can't get much safer for fish than that.