Considerable growth seen on Day 4. The question I’m considering is whether or not the germination rate is optimized? Are some seeds inclined to germinate slower? It is possible that the sauration or drying period between saturation points is not entirely consistent. On a second test the tray will be set deeper into the rock bed, so water flows to 1/2 inch above seed level. It started off that way but the roots are growing straight down, forcing the tray up.