After two years, I finally did my first all grain brew yesterday. For the most part, things went as planned. While batch sparging, I noticed that the water seemed to be channeling to a single spot. I'm using stainless braid, so I thought that might be what was going on, but as I went to stir, I noticed I had a very heavy, dense layer on top of the grainbed, and that's what was causing the channeling. There were no husks or anything in this layer, it was about a half inch of totally impermeable sludge. Was this just the flour setting, meaning I need to mix better? I still hit my goal of 70% efficiency, so it wasn't a problem, but it's something I want figure out before my next brew.