| Maurice,
If you say the bakki shower method works extremely well and produces better water quality and better koi than any other system, then that is good enough for me. However, I cannot accept that is no room for improvement and there is no need to understand the process. If nothing else, the BS method seems a little expensive in terms of the cost of the media and the recurring operating cost for the high flow rates and high water exchange rates. Achieving the same results at a lower cost seems like a worthy enough goal and challenge.
Tewa,
I think you have become hung-up on the statement "The bacteria breaking down dense detritus and living in the base of biofilm is truly anaerobic and will only operate at very low ORP levels". Yes, the bacteria at the base of the biofilm are facultative anaerobes. Yes, these anaerobes are good at breaking down organic matter. However, this is not the only site of detritus digestion. Detritus is constantly being broken down and reformed where ever it exists. There are many pathways and processes which may, or may not, be involved. It includes bacterial attack as well as the action of protozoans, nematodes, etc.
It is important to understand that anaerobic conditions can form at the core of a detritus particle smaller than one millimeter in diameter. While a submerged filter will certainly have many more anaerobic sites, anaerobic sites do exist in bacteria house or any other TT media. In a TT, I suspect anaerobic sites are both fewer in number and more transitory. Facultative anaerobes can go wither way - utilize oxygen when it is available and switch to fermentation when the oxygen is depleted. As the detritus particle is modified by the process, it may crack open, get moved around, etc. and become re-oxygenated. The high flow rates in a BS must certainly contribute to the transitory nature of the anaerobic sites.
The stuff that goes into the pond, must come back out.
My take on the bakki shower method is that pumping directly from the bottom drain and slamming the particulate matter into the media via the high flow effectively erodes particulates and leads to a disproportionate amount of dissolved organic carbon. The dissolved organic carbon is then flushed from the system with the high water exchange rate. Thus, the bakki media will not work without the high flow, and the method as a whole will not work without the high water exchange rate.
In a more conventional koi reactor, the goal is to keep particulate matter intact as long as possible so it can be decanted in a gravity-fed vortex, mechanically captured, etc. and removed. By dumping or back-flushing a small volume of waste with a high concentration of particulate organic matter, you can get the stuff back out of the pond with less water exchange.
In my opinion, the bakki shower method is:
1) a step forward in terms of improved water quality and improved koi quality (because Maurice tells me it is), but,
2) a technological step backwards with respect to producing good water quality and good koi with reduced inputs of new water and pumping energy (both of which are precious and expensive natural resources).
Adding a bakki shower or any other TT is almost always a beneficial addition to a filtration system. However, the bakki shower method, taken as a whole, is not for everyone. If you have issues relative to (a) the quality of your incoming water, (b) the cost of purchasing and pre-treating water for a higher exchange rate, (c) the cost of pumping more water, or (d) the cost of overcoming the increased heat loss, then the BS may not be for you. If you have great incoming water and money is no object, then go for it.
-steve hopkins |