I use a low pressure airlift pump to slowly cycle water and nutrients around plants in an inclined pallet. However it all falls on one spot and there isn't enough pressure to spread it. This is ok until the soil dries out either side of it and then capillary action does not spread the water anymore. So I came up with this to spread the water along the top of the planter. 
It uses a piece of drywall corner metal and when it gets full enough it flops over and empties. Now a full 5 to 6 ft long section at the top gets wet so things should grow much better. The soil is 4 to 6 inches deep and I am also trying "aeroponics" in one section underneath. This section is enclosed with about a 4 inch gap. I have drilled some holes through and I hope roots come down the holes into the high humidity air gap. If things went perfectly moisture might even drip down the roots as the descend. Anyway here is video of the flip flop in action