Rambling About Mud Ponds, Natural Ponds and Koi Ponds

[MikeM]

In another thread we were discussing algae in the water column. It was observed that we might do better for our koi if we could maintain and control a green water environment in a koi pond, and it was commented that filtration based on nitrifying bacteria rather than algae has proved far better suited to koikeeping and the artificial environment of the manmade koi pond. All of which got me thinking about pond dynamics and reading some of the literature on pond dynamics.

Mud ponds and natural ponds are very different from our wholly artificial backyard koi ponds. The natural processes at work are very complex and have to be understood as interacting with several processes occurring simultaneously. When a mud pond is first constructed there is relatively little nitrogen present. Nitrogen is added through fertilizers applied to promote microbe growth as a food for fry, through feeds given to the fish, the wastes fish produce and through the leaves and debris blown in from the surrounding area. Within the water column, harmful (to fish)ammonia and harmless ammonium will be in equilibrium according to the pH of the water. Ammonia can diffuse directly from the pond water into the atmosphere, it is directly consumed by the phytoplankton, it is directly adsorbed by clay in the pond soils, it is nitrified into nitrate by bacteria, and in the anaerobic soil layers nitrate is converted to nitrogen gas which diffuses through the water column into the atmosphere. Studies show that nitrogen leaves the pond system through denitrification and ammonia volatization, with some bound into the substrate clays.

Phosphate is similarly introduced and is rapidly consumed by phytoplankton. Pond soils adsorb phosphates, with clay soils having a great deal of adsorptive capacity. The pond soils gain an ever increasingly high phosphate content in an insoluble form. Organic matter decomposing in the substrate releases phosphate that is quickly bound into the soil. Unlike nitrogen, phosphate does not exit the pond through conversion into a gas. It builds up in the substrate. In a natural pond, rooted plants will extract phosphate from the submerged soils. In a mud pond there are few or no rooted plants and the phosphate concentrations can become quite high.

Clay soils inherently have high aluminum content. Aluminium ions are continuously creating an equilibrium in the soil between the ions adsorbed on soil particles and ions in the water. The aluminum ions will convert to aluminium hydroxide, releasing hydrogen ions, which acidify the soils. The mud pond will be limed to counter this process. The natural pond will reach its own acidic substrate balance, with plants adding different processes.

The newly dug pond has little organic content. Immediately upon being filled with water, this begins to change. Run-off entering the pond brings suspended mineral particles and organic matter. Algae die and settle onto the bottom. Decomposition and mineralization occurs. Simple carbohydrates and protein are quickly decomposed. Complex carbohydrates and cell wall material decomposes more slowly, accumulating on the bottom. Typically in about 4 or 5 years a balance of decomposition is reached. The slow rot is consuming as much of the accumulation of degradable organics as is being deposited on the pond bottom. A gradual thickening of a mineralized substrate then begins, so in the mud pond it is the general practice to drain, till and "renovate" the pond soils at least every 4 or 5 years. A natural pond does not receive such interference.

There is often a misunderstanding that the mud ponds in which koi are raised are equivalent to natural ponds. They are not. They are more natural than our concrete and liner koi ponds, but not really the same as a natural pond. Both, however, are far more complex than our simple koi pond systems. In the koi pond we eliminate the interaction of water with soil...which means we avoid our koi pond water participating in the full range of chemical processes at work. I've not even touched on the ionization of calcium, magnesium, etc., etc. We should never think that we are copying nature. We are not. We use natural processes in our biofilters to serve a goal, but we are very purposefully avoiding as much of the natural processes as we can. We cannot control those processes so well.

[KoiCop]

thanks for putting that together. Made sense, too.

[dinh]

yup, great post.

--Dinh

[bekko]

Nice one Mike.

-steveh

[koiczar]

Mike

Well said - and in terms the average person like me can understand. Puts a lot of things in perspective. How about continuing with the additional info on calcium and mineralization?

Mike

[mitten]

Mike-

Have I misunderstood something then? My impression was that mud ponds were all drained each year.

I do understand that then the pond can dry and rest and restore by interaction with the air. I thought I knew about the maintanence of pushing the clay back, compacting it, liming and seeding with manure to get them started again. It seems from what you've written that this is not for ALL mud ponds, that there is a rotation that does let water remain in some ponds for years. I've seen them dry in Florida and North Carolina, but haven't looked in Virginia or New Jersey or Japan. Help me out.

Mickey the windowman

[johnsmith]

Not drained to the bottom Mickey. And often they fill with snow and rain. They are conditioned periodically to restore function. But this really depends on the ponds use. There are tosai ponds and gosai ponds- they are different.

Actually Mike M, field ponds ( wild ponds, are very desirable it is just that they are more dangerous and not practical for recapture. One of the best chagoi breeders uses a lake! And may used old reservoirs. You really need to get over there and see for yourself. Its all very interesting. I plan on getting back to my twice a year visits again starting in 2007. Let me know if you have an interesting in putting together a ZNA junket.

[PapaBear]

Reality checks are a wonderful thing, and this thread is a great one. I think it would be interesting if all of the experienced and/or well schooled on the topic of mud ponds and natural ponds would chime in as JR has. Getting an accurate picture of water chemistry interactions in these environments can help us all get a better view of the inherent shortcomings of our concrete/liner ponds and help us come up with better ways to compensate for them.

[junglegeorge12]

What Maurice did was mix bentonite with clay, as he saw Momotaro and others do. I would like to know more about the differences you have seen between tosai and other mud ponds.
One of the things I think we will see trend towards in the future is shower or other things designed solely to enhance filtration in the muds, and the natural processes to reduce buildups of undesirable things, but also to oxygenate in order to boost the koi immune systems and increase their eating and grazing to increase growth.

I am wondering about surface areas for growth of thing as well, I wonder if a mix of sand, clay, and bentonite powder woud provide a fuller range of surface areas as versus just one or the other. Here we have the wonderful carribean sun and the natural light to help with the natural processes as well as enhance phytoplankton and algae growths, spirulina seeded in here should produce astounding colors. Anyone know where to buy spirulina or other things to seed into ponds?

[junglegeorge12]

Mitten, the ones I have seen and asked do not drain annually as that would start the whole biological process from scratch, reducing algae and spirulina in the system dramatically. It is only done when needed.