I decided to deal with the heat of my solutions. Cooling them were not so easy. I found that the labortory refrigerator had cooled my reagents to 17 degrees C (at room temperature over 25). The effect was pour - a little smaller pits on the surface. I'm looking for a better way of effective mixture cooling. The second thing was etching the nanoporous layer with 1 M KOH. After that, the nicely textured wafers with low reflectivity, returned to the base materials reflectivity of more than 30%, what troubled me a lot. Generally, this month was not really successful...