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I’m an unabashed advocate for the use of mechanical and biological filtration in aquaponics systems.

It’s also no secret that I regard media grow beds (of themselves) as being inadequate when it comes to mechanical filtration.

So, it’s natural that I would be interested in a discussion (happening on Backyard Aquaponics forum) about filtration – and the perceived need for it….or not!

BYAP member RupertofOz has made this post…..

“Yep, if you’re running a raft, or NFT… you needs some external filtration….If you’re really trying to run higher stocking densities… you probably do as well…But for a normal, balanced stocking density… backyard system…. it’s just not needed….”

So, my question is…..”What is passing for “normal” among the basic flood and drain fraternity these days?”

Everything is normal…..until something changes… which point it is no longer normal (abnormal).  Things are balanced….until something changes and they become unbalanced.

Aquaponics systems are not static; they are dynamic – and (by definition) subject to change.

At what stocking density are things to be consider sufficiently normal – or balanced – to the point where we can safely dispense with mechanical and biological filtration (outside of that provided by media grow beds)?

A few of the things that can change include water temperature, feed consumption, pH, and dissolved oxygen levels.  Even more dramatic changes come in the form of equipment failures or interruptions to power supplies.

Supplementary filtration is fitted to aquaponics systems to cater for those inevitable situations where things are neither normal – nor balanced.