I have just added the following paragraph to the original post above. It follows the paragraph on using a tall fish tank and allowing the water to overflow into the grow beds.

"The problem I have with this fish tank overflow design is that, even though the overflow water is gathered from the bottom of the fish tank, it is not run through a pump prior to entering the grow beds. This allows the fish waste solids to go directly into the grow beds in their sheathed form. The solids I have witnessed and watched on my fish cam are wrapped in a clear sheath, which appears to be the slim component of the worm like solid. By sending the solids through a submersible pump they get macerated, thereby breaking them into smaller components, which allows for the heterotrophic bacteria to do a faster job of mineralization. To leave them in the sheathed form may allow them to accumulate in the grow beds."

Oliver