hi I am thinking about building some raised beds for use in the garden this year. i was looking into self watering alternatives and had some questions. 1) I was looking for an alternative to stone for the reservoir layer can you use wood chips, logs or soil in the reservoir layer or will they draw nitrogen away from the plants roots? 2) Alternatively would you get the same self watering benefit by just putting logs in the bottom then covering with composted soil or do you still need the geotex fabric layer? 3) Finally is there an optimal ratio of reservoir to soil layers. i read about a 1ft of reservoir to 1ft of soil to allow for optimal capillary action