Here we answer frequently asked questions about water chemistry:

What is the difference between mechanical and biological filtering?

What is the biggest mistake that I can make when keeping fish?

I have a bare pond and do not want plants. How do I solve the nitrogen problem?

How risky is it to do without plants?

From which concentration on is nitrate a problem?

What else can I do to stabilise the pond?

Can I do anything wrong with a lot of water movement?

My fish are breathing heavily. Do I have to aerate more?

Excretion is working. Is the excrement on the ground not proof of this?

Why does nitrogen expulsion not work?

And how do I recognise what I have to do?

What does pH tell me?

How long does it take for the biological filtration in a new pond to kick in?

How can I test whether my system works?

What value thresholds are still acceptable?

What are my chances to regulate a system so close to the limit anyway?

Can I send you a water sample?

Do you help with problems?

The pumps circulate the water 10 times per day, but still the fish are breathing heavily. The water is relatively warm. What do I do?

My fish lack oxygen. Why doesn't this get better when I put them in very aerated water with added oxygen?

On the one hand you state that carbon dioxide is a toxic gas, on the other it is supposed to aid breathing. What is correct?

And what is the role of nitrogen in the water?

But normally it is said that water cannot be aerated too much. Is that wrong?

Why are fish so sensitive?

What is the difference between the NaturaGart concept and other recommended systems?

What is the difference between mechanical and biological filtering?
Mechanical filtering extracts particles from the water, for example fish excrements. The biological filtration mainly decomposes dissolved residue with the help of bacteria. This includes all those components that we humans excrete with our urine. These dissolved substances cannot be extracted with filters.
 
The NaturaGart filters are first class mechanical filters. The bottom chamber (BM-13) is the biological module.
 
In normal, natural ponds, every plant leaf and every grain of sand act as biological filters because their surfaces are densely populated with bacteria. In very artificial, bare ponds it would be sensible to equip some of the VF-8 modules with oxy-foam to enhance biological filtration.
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What is the biggest mistake that I can make when keeping fish?
Arrogance! You stand at the shore with a few test strips in your hand and think you can regulate something.
 
A bad pond is like a house of cards. If you change the position of a single card, the whole thing begins to shake. You only know a few of the many parameters to adjust. You then start playing with them and change more than you can see, measure or ever wanted to.
 
You suspect a lack of oxygen and increase water movement, the fish exert themselves in a water treadmill, carbon dioxide levels are depleted and hamper the fishes' breathing even more. The level of pH slowly increases. The fish can't get rid of their ammonia. You add acid to the water and bring the buffering system to its limit.
 
If you want to stabilise your pond's water at these sensitive limits, you'll spend an hour every day with analytics, because test strips have their limits. And what happens if you want to go on holiday?
 
You shouldn't try to regulate the single components. That will not work. Set the general conditions correctly and the system will stabilise itself. Your maintenance is reduced to a few minutes per week - if that!
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I have a bare pond and do not want plants. How do I solve the nitrogen problem?
You don't. The basic problem is that the amount of nitrogen is far to high for the number of bacteria that transform the pollutants. You can reduce feeding so that less is produced. You can create extra living space for the decomposing bacteria. You can use the NaturaGart VF-8 modules for such additional oxidising surfaces. We supply oxy-foams with pore sizes that ensure a sufficient supply of oxygen.
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How risky is it to do without plants?
A pond with plants has several levels of safety: Plants absorb different nitrogen compounds directly from the water and bacteria take care of additional transformation
 
If you do away with plants you rely solely on bacteria, and those produce ever more nitrate that'll become a problem in the end.
 
From our point of view you cannot do away with plants!
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From which concentration on is nitrate a problem?
90mg/l are a very safe value and many fish can surely handle multiples of that value.
 
You can partially change the water when nitrate concentrations surpass those 90mg/l.
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What else can I do to stabilise the pond?
Regularly check pH. Keep it below 7 by filtering with peat.. 
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Can I do anything wrong with a lot of water movement?
Yes! You drive carbon dioxide from the water. Fish can choke even if there is sufficient oxygen in the water. Also, biological filters nay possibly not start up well.
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My fish are breathing heavily. Do I have to aerate more?
Could be. But perhaps not! If you step into clod water, you also begin to breathe heavily. That has nothing to do with lack of oxygen. From the fish's breathing you can only see whether the it has a problem - but not what that problem is. The movement of the gills doesn't only serve the intake of oxygen, but also expulsion. Which part isn't working is not recognisable from the movement.
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Excretion is working. Is the excrement on the ground not proof of this?
No! 90% - 95% of nitrogen that we excrete through urine, leaves the fish's body via the gills. You cannot see this.
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Why does nitrogen excretion not work?
You may understand this better through an example: Two rooms, one next to the other, have a difference in temperature of 10ºC. If you open the connecting door one room loses warmth until both have the same temperature. Without a lot of machinery it will be difficult to extract heat from the cooler room to heat up the warmer even more.
That is exactly the problem that fish have. They expel nitrogen as ammonia and tat is only possible if the surrounding water contains practically no ammonia.
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And how do I recognise what I have to do?
You have to know the general conditions. Those can be estimated as probabilities. You can get test strips for pH, nitrite, nitrate and ammonium. Oxygen measurements are usually too costly and electronic devices normally have to be calibrated and need maintenance. Carbon dioxide is also difficult to measure because it is also contained in the water's hardness factors that can quickly change results.
By moving the water it is easy to reach 100% oxygen saturation, so that is usually not the problem.. 
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What does pH tell me?
This value alone: close to nothing! It can vary by 3-5 points during the day. Your point measurement can thus be completely worthless. You should know the hardness, the intensity of water movement, the amount of plants, the proliferation of algae, the age of the pond, the volume of water and the fish population.
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How long does it take for the biological filtration in a new pond to kick in?
Conventional wisdom says: Throw 'starter bacteria' in, turn on the pumps and aerate. Reality, however, is somewhat different, and the following conditions should be known.
 
Start-up inoculation:
This is usually completely overrated. The types of bacteria are very common and they tend to multiply at the speed that water fills into the pond. It is more important to realise that they hardly find nutrients for growth in newly built ponds and that therefore they aren't necessary yet.

Consequently...
this means that from our point of view 'bacteria starters' are of no practical importance.
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Oxygen:
With little oxygen the bacteria grow fastest. In some experiments we reached maximum decomposition efficiency after 3 days. Only when the bacterial growth rate reaches the exponential phase, oxygen limits their activity. Then growth continues optimally at 100% saturation.

An excess of oxygen can completely block bacterial growth. This happens, for example, in extremely aerated basins. Some experiments have shown that even after 400 hours no notable growth takes place. This seemingly surprising effect is a defence mechanism the bacteria use against the aggressive oxygen. They begin to produce an enzyme (superoxide-dismutase) that protects the cell against oxygen radicals.
 
Consequently...
it is a grave mistake to intensively aerate new ponds from the start!
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Carbon Dioxide:
Bacteria don't decompose toxic substances out of nicety, but because they feed on them. However, to grow they need other nutrients, and especially carbon dioxide.
The carbon it contains is essential for cell growth.

Consequently:
carbon dioxide is driven out of the water by aeration equipment. Less water movement is better. Oxygen is very rarely a problem.
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 Light:
Even at 420 Lux ammonia decomposition can be mostly blocked.

Consequently...
some filtration systems are installed in places with too much light, are made of transparent materials. The NaturaGart filters are completely opaque.
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Interruption:
The second step in the decomposition of nitrite to nitrate can be disrupted. This means that nitrite accumulates, which makes decomposition even more difficult. Optimal efficiency is reached when decomposition runs at the same time. This requires capacity reserves.

Consequently...
systems that function at the limit have few reserves. Interferences can massively disrupt decomposition efficiency.
Increase filtration surface and/or use plants.
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How can I test whether my system works?
Measure pH, ammonium, nitrite and nitrate. Ideally all nitrogen exists in the form of nitrate.
 
Higher values of ammonium and pH above 7 are always critical because they can disable the fishes' 'kidney system'. Sturgeons are especially sensitive, since they expel 98% of oxygen through their gills. High nitrite values block the blood's oxygen transport capacity.
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What value thresholds are still acceptable?
This depends on the different species, because not all are equally sensitive. Also important are the fish's vitality, pH and temperature. Here, too, everything depends on everything else.
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What are my chances to adjust a system so close to the limit anyway?
If you are skilled and constantly observe the pond closely enough, you have a good chance to prolong the period before major disruptions occur. But we always talk about w h e n these disruptions happen, not whether they will happen at all. They will!

Even those who propagate these sensitive systems regularly suffer large losses. The much loved koi are so expensive, among other things, because the breeding risk is high and any sale must also cover the deaths that occur at the same time. Any importer can tell you a thing or two about this - all the way to bankruptcy...
 
If you want to run such an unnatural system perfectly, you quickly become your pond's slave. 
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Can I send you a water sample?
Wouldn't make much sense! Water changes within a few minutes. Measurements have to be done at the pond - or the sample has to be 'fixated'. Not everyone can do this, though.
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But water tests are offered in many gardening centres. All humbug?
Mostly! As soon as the sample's temperature changes during transport, most other characteristics change, too. The more critical the characteristics are, the quicker they usually change. Really important things are not measured anyway. Most analyses are just marketing circus. 
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Do you help with problems?
That depends of how co-operative the pond owner is. In most cases the ponds are designed by us which means we have set the correct general conditions and there is practically no problem.

Then there are people who don't stick to the rules, constantly try out something new and stumble from one problem into the next. In these cases we will withdraw at some point.

In concrete: Ideally the whole installation is from us. Then there will never be problems. We help until everything runs smoothly again.
 
When we supply components, such as filtration systems, you get all the information necessary to set general conditions correctly.

If you have bought everything somewhere else, then please go there to get a solution for your problem.
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The pumps circulate the water 10 times per day, but still the fish are breathing heavily. The water is relatively warm. What do I do?
Stop feeding them! If the fish can't expel the nitrogen, you shouldn't be giving them more! Try reducing water circulation; that'll make breathing easier.
Circulate the water through a basin with plants!
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My fish lack oxygen. Why doesn't this get better when I put them in very aerated water with added oxygen ?
Because all the water movement drives out carbon dioxide. The oxygen can stay, but reduce the flow (so that the CO₂ concentration can rise) and stop the aerator.
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On the one hand you state that carbon dioxide is a toxic gas, on the other it is supposed to aid breathing. What is correct?
Both! Not everything in life is black or white. Sit down in an armchair and breathe deeply and quickly 10-20 times. You'll notice that you get dizzy. You have enough oxygen, but you have expelled too much carbon dioxide. Something similar happens with the fish. Below 0.5mg/l the state always becomes critical, below 7mg/l problems begin. The ideal range is between 7 and 18 and things become critical again from 25mg/l. Many ponds reach the lower threshold in summer and the upper in winter.
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And what is the role of nitrogen in the water?
Most important the compounds that contain nitrogen, such as ammonium, nitrite, nitrate and nitrous acid.
Gaseous nitrogen becomes a problem when water is over saturated under pressure. This sometimes happens in trout ponds where water falls from great height, brings along nitrogen and dissolves it under pressure.
An over saturation of but 1% leads to the development of micro bubbles, 3-5% over saturation are critical, and more is usually fatal. Like with divers' decompression accidents, nitrogen bubbles form in the body that lead to paralysis and even death.
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But normally it is said that water cannot be aerated too much. Is that wrong?
That is merely the argument of greedy pump dealers. We usually sell pumps that are 3-4 power levels below those sold by common dealers. Not only is that less expensive for investment and operation, it is also better for the pond.
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Why are fish so sensitive?
Life is always, also for us, in a precarious balance. A few percent more oxygen and earth would be uninhabitable, because things would catch fire very quickly. A little more CO₂ and we'd stagger around as if drunk.

Air breathers like us have an advantage that air can easily reach the lungs. Water is much tougher and can only be moved with a great deal of strength. Purse your lips and try to breathe only through your mouth.

The muscles in your chest now have to work much harder to supply the lungs with sufficient air. This is how a fish feels when it breathes. Half of all its effort goes into breathing - we use only a few percent. Therefore it is sufficient if we can exploit about 37% of the oxygen we breathe. Fish do 60-80%. They need this safety reserve. Wrong conditions of fish keeping quickly over strain them. We can increase our breathing frequency quite a lot. Fish work at the limit while seemingly at rest.
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What is the difference between the NaturaGart concept and other recommended systems?
Here biologists rather than fish salesmen are at work. We don't trade in fish. We have no financial disadvantage while being objective. That is one thing.

The other: Nature has developed survival strategies for the species over millions of years. From our point of view it is sensible to install these natural regulation systems.

We therefore tend to adjust the general conditions and not the details. They will then adjust themselves.

Others fiddle around with the details and constantly shift the general conditions. That will never lead to stability.
 
Some fish keepers remind me of people who want to cross a canyon on a tight rope. They build a safety net, wear special shoes, strap on leashes and take ages to get to the other side.

All this while they could've used the existing bridge a bit further on...