Hey everyone. It's been a while since I've been here. Sue's kept me pretty busy this summer. In the past I've had abundant opportunities to work with both marine and freshwater bacteria concentrates as they apply to very large, enclosed systems (public aquaria type settings). What I can tell you is that the bacteria that I used significantly reduced the amount of nitrogen, and muck buildup in a good portion of the filtration.
However, I need to qualify that by saying that these systems, just as any natural ecosystem, have a natural carrying capacity for every trophic level in it. The bacteria we used may or may not have been the same species as what was already in the system (I didn't perform any research on the topic, just noticed and can report on the results). The reason for adding the bacteria was also different in these circumstances. It was generally used for "quick start-up" or emergency "dangerous nitrogen level" situations. These situations would generally not apply to the pond community. They were added to temporarily BOOST the nitrification and detoxify the water, in order to save the fish. A side effect was the reduction of muck that had built up in well seasoned systems.
I mentioned the term carrying capacity earlier. Let me elaborate. Due to the fact that even a large pond is a relatively closed system, it will have carrying capacities (maximum sustainable numbers) for all of the species it contains. This includes everything down to the bacterial level also, and is influenced greatly by physical circumstances that put limits on what can survive, and in what numbers. A natural checks and balance system.
Bacteria reproduce very quickly. Their life cycle is generally very short. Most new pond owners are not in such a hurry to get things going that they have the need for "jump starting" the pond when it will only help them by a matter of a few weeks. In the same respect, most ponds will not experience a catastrophic nitrogen spike overnight (unless SIGNIFICANTLY OVERSTOCKED ALL AT ONCE).
The nice "side effect" that seems to happen, at least in my experience, is that there is a slight muck reduction by using the type of bacteria that I have, in the past. I'm not sure if these are the same species of bacteria that are available for the pond scenario, but it would stand to reason that they would help in that respect, to some degree. Further research is definitely warranted in order to gain quantitative data.
To address Loretta, the reason that your bacteria worked in the shallows (without aeration) is because these bacteria are aerobic, and require certain levels of oxygen to survive. Your pond is most likely stratified to some degree, preventing decent oxygen levels in the deeper areas, and therefore preventing the muck reducing bacteria from being able to reach the muck in the deeper areas. This is why aeration helps. Properly sized aeration will circulate the water from top to bottom, bringing the oxygen levels in the deeper areas up to sustainable levels for the bacteria to survive and start breaking down the muck.
Once the pond is de-stratified, the natural bacteria of any pond will quickly reproduce and begin to break down your muck for you. However, depending on other parameters of your pond, "quickly" can be a few months to a few years. Bacteria are very pH and temperature sensitive, and significantly slow down or stop when exposed to parameters that are outside their "norm".
The reason people have to keep adding bacteria, as you mentioned, is most likely due to the fact that their pond is already at the carrying capacity for that type of bacteria, and after some time, start reducing in numbers again, in order to get back to the natural maximum sustainable number for that species.
While I personally don't disagree that the addition of bacteria can help, I question the generally huge expense associated with it since a pond with decent circulation and oxygen levels to the bottom should be able to maintain a healthy population of muck reducing bacteria on its own. But as I said, I do think that more research is CERTAINLY warranted.
Hope this sheds a little light on the subject.
