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Mechanical Filtering
When fish disturb the sediment or tiny algae make the water go green, foam filters that collect these particles are used. Sediment free ponds are a strategic goal for fish and swimming ponds. The closer to this goal you get, the clearer usually the water will be.
Particles can be filtered out - but that is not everything!

Problematic Dissolved Substances
You can pass your coffee through the coffee filter for as long as you like, it will not change colour, because the dissolved colour substances pass even through the finest filters. In ponds, phosphates, rests of proteins such as ammonium, nitrites and nitrates behave like this. Only so-called ion-exchangers can retain these dissolved substances that are important algae fertilisers.

Each foam element in a NaturaGart filter can hold up to 1kg sludge; a standard filter holds up to a total of about 9kg.

Biological Filtering
Protein residue will first form toxic ammonium and nitrite. Helpful bacteria transform these problem substances into relatively harmless nitrate. In the world of aquariums a frequently asked question is: how can the work that these bacteria do can be aided by using special filtering media. It is often overlooked, however, that these bacteria colonise every grain of sand and every plant leaf. They begin to form within a few days and are usually present in abundance.
Solve the Problem at the Root
The NaturaGart concept solves this problem one step earlier: Underwater plants can (unlike most land plants) use ammonium and nitrite as fertilisers. When the problem substances are thus incorporated into plants, the whole discussion about further treatment becomes obsolete.

Example values for nitrate:
Plant-less ponds: mostly far above 100mg/l
Limit for drinking water: 30-50mg/l
NaturaGart ponds:          5-10mg/l
Underwater plants play a central role for NaturaGart - and for nature.

Risk: Plant-less Fish Ponds
Here protein residues keep accumulating. The water is trickled over a large surface area. Bacterial action will decompose the most toxic intermediate steps, but will not solve the problem. Nitrate remains in the water and can quickly transform back into poisonous nitrite.
In many ponds algae take care of this problem by consuming the nitrate. The pond survives.

Algae as 'Last Line of Defense'
If such a fragile system is deprived of the algae, collapse is inevitable: No more nitrate is consumed and increasing oxidisation surfaces will only be an emergency solution as long as toxic substances are only transformed and not consumed. The NaturaGart filtration trench is the ideal solution to this problem.

Nitrogen from proteins is best incorporated into the plants of the NaturaGart filtration trench.

Transformation of Protein Residue
The pond sediment contains protein residue. An intermediate substance first forms as (poisonous) ammonium. This is either incorporated by underwater plants or transformed into (still toxic) nitrite by bacteria. Another type of bacteria then transforms that into (relatively harmless) nitrate. This transformation takes place on surfaces that are colonised by bacteria. Any enlargement of this surface is therefore helpful.
Comparison: Nature and Technology
In natural ponds bacteria colonise every grain of sand and every plant leaf.
In bare liner ponds usually foam, filter brushes or granules are used. The problem with most methods is that the water flows much to quickly. Many hobby-filters probably stabilise ponds only minimally. In fish ponds the number of fish and the volume of water determine the size of the required filtration. 
Natural ponds are stabilised by sediments and plants alike.

Visibility as a Criterion
In deep and large ponds more suspended particles exists between the fish and the viewer, so you can't see them very well. The depth of the water and the size of the pond therefore determine the required filtration. Looking vertically into a small pond, there may only be one metre of water between you and the fish. In large ponds it can be several metres.
Swimming and Fish Ponds
differ mainly in the influx of nutrients. In ponds with fish these are fed, so there are more protein residues. In most private swimming ponds nitrogen isn't a problem.
Well kept (sediment free) ponds usually have a tenth of the allowed concentration for drinking water. After the initial stabilisation phase these ponds are usually clear.
The plants in the filtering trench consume residuals that the pond doesn't tolerate.

Flow Rate
Each filter is built for a certain amount of water. If too much water comes in, pressure-less filters overflow, pressure filters may even burst.
This theoretical amount of water is reduced by the increasing resistance of the filter. The more dirt accumulates in it, the longer it takes for the water to find its way through.
To Think is Better Than to Pump
Many are interested in selling strong pumps. The filtration media that go with them are relatively coarse because only large holes let pass so much water. The NaturaGart system works like your coffee machine: One pass must be enough. That is why the NaturaGart filtration media are much finer. Even with its much larger filtration surface, a NaturaGart filter reaches its limit with a flow rate of 70 litres per minute.
The organic mats in a NaturaGart filter are extremely fine.

Filter Resistance
The more sediment is deposited in a filter the more difficult it is for the water to find a path through the filtration medium.
Many systems solve this with powerful pumps that push the water through the foam.
The NaturaGart filtration system has a series of reserve modules that become effective when the first ones clog up.
Pond Geometry
The shape and water flow in a pond is important for the filtration system. When, statistically, all the water in a pond has passed through the filter, some water will not have been through the filter at all and some will have passed it several times. Only long, stretched out basins with inlet and outflow on opposite sides are filtered well. The shape of the pond determines the rate of circulation.
For ideal aspiration NaturaGart has developed the Target Suction Technology.
For ideal aspiration NaturaGart has developed the Target Suction Technology.

Circulation Rate
For most ponds it is sufficient if the volume of water is filtered once or twice per day.
Ponds with very large populations of fish usually have to be filtered 3-5 times per day, depending on water temperatures.
In swimming ponds a much lower circulation rate is enough because of the low levels of nutrients.
Service Intervals
Customers who buy a NaturaGart filter are sometimes confused at the amount of mud that the filter retains. The reason is that these filters do their job extremely well. It is supposed to filter out particles, so that is what it does. Many ponds have a backlog. After the initial cleanup cleaning intervals are usually up to a few weeks.
The NaturaGart coarse filter extracts large amounts of suspended particles.

Seasonal Adaptation
Cold water needs much smaller circulation rates. Many filters, however, are used all year around with the same intensity. In large ponds with several modules part of the system can be completely shut off - this reduces maintenance and costs. In the winter filtration helps to reduce the concentration of carbon dioxide.

Adaptation to Particle Size
I spring a large proportion of coarse filtering is required. Later the activities of fish and ground animals leads to more fine particles. Now it should be possible to reduce the size of pores in the filter. When the foams clog up evenly, the filter is most effective. The NaturaGart filtration system allows for such adaptation, unlike most others.

Wir haben die NaturaGart-Filter bis -15°C betrieben. Das Wasser läuft dann unter einer schützenden Eisschicht.

Note Fish Growth
When fed well many fish will only grow 2-3 times their size after the first year. If you only look at the length, you may conclude that the load for the pond is therefore only 2-3 times what it was before. This, however, is wrong, because the weight of the fish grows 30-50 times in the same period, because they become heavier. The burden for the pond increases accordingly.
Multiple Factors
This is how risk changes:
  • Many times the amount of feed
  • Many times the amount of excrement
  • Many times the consumption of oxygen and ground raking
A higher burden automatically also means that reserves for wintertime diminish.
Often a few more days of frost are sufficient and life in the pond dies...
Especially with Koi the risk that grows as the fish do is underestimated.