'Apples': "The drainage studies are disproving the effectiveness of a layer used in improving drainage (from the soil layer) within the container". 'Oranges': "you're advocating its use as a capillary break to prevent a plant from drowning in a pool of excess water that has already drained". These are clearly two different applications. In the 'Apples' scenario the perched water table is constant, with its size unchanged by the introduction of a rock layer so there is no extra water drained from the soil layer. Conclusion: The rock layer serves no useful purpose in this application. With the 'Oranges' scenario, I acknowledged the use of the layer as a capillary break to be valid and that it has its uses by saying, "As you pointed out, a capillary break has its uses in certain situations but in most cases it would be simpler just to make a practice of emptying the saucer." Yet you ended up repeating yourself in citing an example which you provided earlier. I do not disagree with either the layer's application as a capillary break or with the example given. You haven't added anything new to the discussion. Furthermore, by acknowledging the valid use of a capillary break in certain circumstances, are you not also tacitly agreeing that it does not need be installed in ALL cases? Are we then not in fact in agreement on this particular application? One can easily see the amount of water in a pebble tray by sloping the layer on the edge bordering the tray. Alternatively, an open-ended cylinder can be inserted vertically into the layer so that the water level can be seen. Once again, there is no need to install the capillary break inside the container. I acknowledged that point by saying, "In order to not reduce the amount of usable soil, the original volume of such has to be maintained and in doing so necessitates the use of a taller container than otherwise required." Yet you launched into a long diatribe on scientific methods. Please tell me how you would introduce a new layer of material, while keeping the existing soil without the use of a larger container. In the playing field scenario, the capillary break allows water to drain into the tile layer while preventing water from wicking back up. But with a container, there is no need for such a layer as long as the saucer is emptied of its contents. There is nothing new here as this is the same as the 'Oranges' scenario.