I am looking to use 15 inch planters for sarrs and wondering if this setup would work. I am using a planter with a drain drilled in the bottom which will be capped so I can change the water out every so often or right before it rains. The bottom will have a 2-3 inch space with no soil (using PVC for a plastic grid to sit on. On the grid will put plastic). I will also have a tube coming down to fill the pot as well as an overflow about 6 inches from the top. Attached is a picture sort of explaning (hope it works). Any help would be greatly appreciated.