Ok, I'll give it a shot
My idea is in a way, a super simplified version of Heaths setup. It would allow for scaling and portability, but may be missing a few perks of Heaths, since the angled tubed would mean, if the pump stops, the water drains off all the roots rather quickly. Let me try to make a sketch of what I am thinking, although its hard to make a 3D version to describe what I want to do. Heres a go
First step: make an (imaginary) circle on the ground, in general this will be the size of your surrounding area. Imagine the red circles are PVC tubes (3" or whatever size works) looking strait down.
Next step, is each tube, we angle sideways, I'm thinking between 30-50 degrees off the floor. So, if the PVC pice was 5 ft tall before, now it will only be 2-3 ft off the ground. We angle all of them to make a spiral type shape, so none of them touch eachother (each tube angled exactly the same off ground).
Heres a really really bad side view, but you kind of get the picture. With this system, you could arrange 2 of the PVC tubes to be mounted separate, so you could 'roll' them out for inside maintenance
easy.
Basically, there would be detail work with the water connections, but essentially 1 pump feeds all 5,6,7 or 8 PVC tubes equally from the top (may need irrigation adapter for this). Then, the water just flows down each tube at whatever angle, and you collect it at the bottom some way.
This uses only strait sections of PVC tubing (3" or 4"), thus eliminating all connecting parts, or bending/warping connectors to make the special spiral that is awesome, but difficult to reproduce. This would have constant water flow, unlike Heaths system where the PVC tubes are level, so water can "sit" there if the pump is off. If the pump breaks, then there is no water pretty quickly as it would all drain (unless anyone can think of a work around, maybe damming each plant location partially to store some liquid.)
Wonder if anyone thinks this is feasable. I'm not sure if I will be able to test it, since sea of green requires lots of plant #'s, which I may not be in the position to do currently. Someone without plant limits may want to try this type.
For draining and changing the resoivior, simply turn the pump 'off' and all the water should collect within a minute or so. Or, you could perpetually adjust the PPM by interacting directly with the res only, while the pump is running. Heath mentions that salts (things not used by plants build up) can build up if you do not completely change the water every few weeks, although I have heard elsewhere you may be able to get around this...