The idea of the grow bed is to "NOT" over water....MJ plants like a dry climate and will thrive with proper feedings and waterings....considering the other requirements of the environment are met....like humidity and temperature.

By not over feeding or overwatering...the bed is designed to have enough aeration and relies on you; the gardener, to water just enough and not go beyond.
Flushing of a properly built organic soil or soilless medium isn't needed if the correct amounts of ferts and nutes are used.
True organics not have salt buildups.

Buddah if you're going to grow in a reduced scale bed ....remember to stick as close as possible to what Soma uses....I'd like to be around when you get this bed going. It's going to give you lots of buds and healthy plants.

Then when it's done....I have some info that the 3Little Birds (3LB) posted about reusing organic soil. Do a google search on 3LB or 3 Little Birds and growing...they have some great info you might be able to add as well.