Thank you Azi, I'm taking longer to understand this setup than the others I'm sorry. I can't grasp what you're saying about pouring into a void and about the fill pipe connecting to the air gap.If, on the other hand, your lower area is filled with soil around the dome, you'll want the water you are pouring in to have a void to flow into to speed up the watering process. Also, if the fill pipe isn't connected to the air gap you'll have less air down there by the roots.
Here's a diagram of what I think you mean. Please remind me how the wicking action takes place in this arrangement, or am I missing a component? Does this adequately take care of the air gap and void? Also, at what level should the overflow hole be drilled in the dishwashing tub? Is the pasta strainer full of water and nothing else? Where does the soil cup come into this settup? tia AziIf you are using hydroton in the reservoir you can absolutely have the fill pipe go straight down into them. That's the way I built my outdoor veggie tubs. Another advantage of having it dead-end at the clay balls is that the air gap will have constant access to fresh air.