I use 6qts with four holes melted (one on each corner) and the lid snapped on. Vermiculite is approximated, just enough so that it clumps like a snowball but no water seeps out. When i check the eggs i pour the condensation on the lid back into the vermiculite (but not on the eggs).

Worked fine for about 50 eggs I incubated last season, only had a few go bad and they didn't look good from the start.