TEWA: I think you are mis-reading JR's posts. There are several separate points he is making. The first is that a Bakki Shower used as the sole filtration is not the same as a trickle tower. A corollary is that a Bakki Shower used as an element of a filtration system composed of multiple sorts of filtration is not the same as a Bakki Shower used as the sole filtration. Separate from these points is his series of questions regarding the sufficiency of Bakki Showers as a sole filtration system over time. He does not say that there is a build up of organic sludge, but asks the question of whether there will be. He does not condemn the Bakki Shower system as a sole filtration system. Rather, he raises several questions about that application and explains the biology behind his concerns. He awaits the real world results of hundreds of koikeepers using the Bakki Shower system over a period of years, not just on water parameters, but on long-term fish development.
I would agree that JR has posited many challenges to the Bakki Shower system as a sole filtration system, but he does not go so far as to reach a conclusion against the Bakki Shower. What he does do is explain why there should be thoughtful caution before taking up the fad of the day. Some fads become conventional wisdom in time; but most fail under the harsh reality of real world experience.
We know that a crucial element of the Bakki Shower as a sole filtration system is the 10% daily fresh water infusion. It is key to Momotaro application and proved key to SMG's experiment with Bacteria House and lava rock. An unanswered question is whether that 10% infusion could take the form of a water change, or does it need to be a continual in-flow? I suggested that either was effectively the same (without referencing the Bakki Shower) in a different thread over on that board. Steve Childers immediately disagreed in his usual strong terms. [I chose not to debate it with him, since I do not know the real world answer; but do know that he and I would never agree on theory ... SteveC never agrees once he has said he disagrees.
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Anyway, review JR's posts again and I think you will find that he does not go as far as you are thinking. .... and I'll be quiet and let JR speak for himself if he wanders over this way.