Originally Posted by Woodswalker
I'm probably a weirdo here, because I build a false bottom, then add a layer of hydro balls on top of a sheet of window screen, then another sheet of window screen topped with charcoal, then my ABG on top of that..
That's exactly how I do it, although the charcoal (in my case bio char- same diff) is mixed in with the ABG. Or, recently, Ive been doing some vivs with Turface.
But basically: Eggcrate spacer to create drainage layer.- fiberglass screen Hydroballs on top with another screen and finally: "soil".
The water level floats somewhere in the hydro ball layer. The drainage layer allows for active diffusion of nutrients (and toxins, in some cases, I suppose)- and of course is the place to drain it all from if necessary. If the tank doesn't have an over-flow, you can stick a section of straight rigid airline tubing down to the bottom and with attached flexible airline tubing make a siphon and drain it. The bottom reservoir of water makes draining easier, IMO.