To stir or not to stir?

[resonator]

My last venture into the realm of low tech planted tanks came to a frustrating end when I stirred my substrate.

I'd had the tank running for about one year. The substrate was simply pool filter sand (probably 1mm to 3mm in size) and was about 2" deep. It was sparsely planted, but the plants that I had were doing fine (crypts, wisteria, moneywort) & were all surviving with slow/steady growth). I even had a single Cory cat who would sniff through the topmost layer of the substrate, just doin' his thing.

Well, I don't know what got into me, but after about a year, I decided that maybe I should stir up the full 2" of PFS manually for the first time since the inception of the tank. Big mistake. The water turned cloudy almost instantly, the smell of rotten eggs (Hydrogen Sulfide gas?) permeated from the surface of the tank, and I lost most of my livestock within a few days.

So obviously I did a bad thing by mixing it up. Question is, had I left it alone, would things have continued just fine. Or ought to I have been stirring all 2" of the substrate much more frequently (weekly perhaps) from the get-go? What do you do with your substrate?