The 10 Greatest Pond Myths

There are countless myths and care tips about pond and pond care. Some are right, others you can safely forget. You can find out in our series of pond myths whether cheap food is of good quality, whether koi adapt to the pond size, and how you can get a grip on algae.

There are innumerable pond myths. Some are right, others you can safely forget.

Myth number 1: fish adapt to the size of the pond

Goldfish and Koi are now bred in countless colors and unusual shapes. Some of them are so beautiful that one or the other pond friend cannot say “no”, even though the pet shop seller clearly pointed out the possible final size of the animals. Even if your own pond only contains 300 liters, for example, the little Koi has to go home with you. The neighbor once said: fish adapt their size to the pond. However, this assumption is wrong. Fish do not have a conscious control function to adapt their growth to their environment. But why is the one fish in the big pond from the neighbor much larger than your own fish in the balcony pond, even though the fish come from the same dealer?

In small bodies of water, substances that promote growth, such as minerals and vital substances, are used up very quickly, as the stocking density is often significantly too high. The swimming space is also often very scarce, so that joyful swimming around, which promotes digestion and metabolism, is hardly possible. Substances that slow the growth of the fish also accumulate very quickly. In particular, the metabolic end product of the filter, nitrate, is responsible for poor development in high quantities (more than 50mg / l). In sufficiently large ponds, due to the lack of space, there are significantly more options for planting nitrate-degrading plants or using mineralizing decorative stones. “Wrong development” is the more appropriate description for this myth.

Myth number 2: skincare products are chemical and harmful

“I am not a fan of chemistry in the pond” – one reads and hears very often in forums or conversations between pond owners. But is it really chemistry that we pour into the pond in the form of powder or liquid as a care product? The “remedies of the 80s” were often of a chemical basis and only had the aim of inevitably killing algae spores and clarifying the water for a long time. Unfortunately, these remedies also destroyed valuable microorganisms. For some years now, the trend has been moving in the direction of the natural way of life. The industry quickly recognized this trend and is fulfilling its customers’ wishes, also because the legal situation is clearly devoted to nature conservation and many “old” active ingredients are forbidden every year. Modern preparations work together with nature and promote biological processes.

Most modern algae killers and care products consist of purely natural substances that bring the water budget into balance because previously there was an unequal relationship between dirt entry and degradation. The main ingredients are, for example, monolinuron and copper sulfate. Copper is an important building block in life. It is found in a large number of foods, such as fish, ruminant entrails, nuts, coffee, and vegetables. Even the Federal Office for Risk Assessment recommends daily intake. Copper is also deliberately added to most feeds for koi and goldfish in order to prevent deficiency symptoms. In slightly increased concentrations, however, it is incompatible with primitive algae and leads to death.

Other parameters of the water are also corrected and maintained in a purely natural way. The water hardness and the pH value are treated with bicarbonate and calcium, algae preventive preparations are also based on minerals, sludge remover and filter booster consist of “good” cleansing bacteria. When buying products from German retailers, you can access them with a clear conscience, as long as you follow the instructions for use.

Myth number 3: the pond regenerates on its own

Yes and no! To explain this, we take a lake as an example: There are plants on the bank. In autumn leaves wither, they fall into the water, sink to the ground, where they are gradually broken down by bacteria in meter-thick layers of the substrate and release nutrients into the water that are ultimately consumed by algae. The degradation process consumes minerals that are redissolved by the natural rock on the shore or in the lake bed and are available to the ecosystem again. The relationship between the amount of fish and the volume of water is unequal, so a fish swims in several thousand liters of water. The lake depth of 30 meters or more guarantees an even temperature zone distribution for all residents and protects against overheating.

In the pond, however, the water is insurmountably separated from the environment by the pond liner. Natural nutrient seepage sources, therefore, do not exist. There is a lack of meter-thick layers of sediment, so that waste products cannot be sufficiently recycled, accumulate, and create poor climatic conditions. Most ponds are also (extremely) overstocked with fish. The dirt removal process has to be kept in full swings, like an engine at full throttle.

These circumstances lead to a very high “consumption” of vital substances, which pond lovers rarely add sufficient amounts to. The system is not round and leads to collapse without “artificial” correction. These corrections are necessary because every traditional pond created with a pond liner, filter system, etc. is still artificial. There are ponds that have flourished for many years without extensive care (products), but this harbors dangers that are often underestimated. At some point, the elementary nutrients are used up, so that the pond can tilt overnight.

How do you prevent it all? Carry out regular water tests (weekly to monthly), carry out sufficient partial water changes (approx. 10% per month), and ensure sufficient water hardness (KH at least 5 °).

Myth number 4: Food is the same as food

You can certainly feed your fish with cheap food, but if you’re wondering why others pay a lot more for pond food, the answer is quite simple: Expensive food is cheaper!

Food in the middle to higher price segment costs a little more money because protein as a raw material has its price. Protein, this is not a new finding, gives a lot of energy, is easily digestible for the organism, and keeps you full for a particularly long time. Good goldfish and koi food are usually pressed in granulate or pellet form so that ten times the energy can be found in one liter of pellets than in one liter of foamed sticky food.

Example: If you were to feed four handfuls of sticks a day, a shot glass full of pellet feed would be enough to satiate the animals. The quantities of excretions are correspondingly lower since protein-rich concentrate is almost completely utilized. Fewer droppings mean less dirt/algae nutrients, you have to clean the filter less often, spend less money on anti-algae agents, see your fish swimming around in a much nicer color, and experience fewer problems overall, such as fish diseases and sludge deposits.

Tip: Pay attention to the corresponding water temperature information for the food on the packaging! With good feed, the nutrient content is adapted to the respective seasons. Summer food in spring is like a greasy pizza immediately after a zero diet.

Myth number 5: Koi are more sensitive than goldfish

That is not right! They need almost the same water values ​​as goldfish and are anatomically very similar. Koi are only cared for in a less appropriate way. In this context, you should know that Koi have a very high metabolism and energy requirement. If the Koi keeper does not pay attention to this and only rarely feeds or offers poor quality food, deficiency symptoms are the real cause of common diseases that are rarely recognized in time to be cured. The possible final growth size of up to 1.20 m is also rarely taken into account.

As a yardstick for a sufficiently large pond, there are various rules of thumb from which a basic one has been established: A koi pond should contain at least 5,000 liters. Since Koi are group animals that communicate with each other, the group should consist of at least 3-4 animals. 1,000 liters are reserved for each animal so that a Koi group needs 8,000-9,000 liters of space. By way of comparison, it should be mentioned that a single koi with a body length of 20 cm secretes about the same amount of feces as 30-50 goldfish of the same size. If you do not adapt the filter system to these dimensions, the germ pressure of the water increases extremely. A smoke-filled and overcrowded party room would have a comparable room climate. If you follow these tips, your Koi will stay healthy and forgive you for minor careless mistakes.

Myth number 6: You can turn off the filter

There are certainly reasons to switch off the pond filter in the meantime. From a biological point of view, however, these do not make sense at all. Sometimes your neighbor may complain about the noise of the water, or you are afraid that the hose will jump off in your absence and the pond will empty, or you just want to save electricity and only let the filter run for hours. Unfortunately, then the filter has even less effect than not running it at all.

What happens inside a pond filter? Dirt and waste materials are mechanically captured in the first filtration stage. In the second stage, billions of bacteria break down these deposits and toxic substances or convert them into non-toxic metabolic end products. In this phase, the cleansing bacteria require enormous amounts of oxygen, sometimes more than all fish together. Several weeks may pass before these processes function fully, stably, and actively. If actively living bacterial preparations are dosed, in the best of cases, it only takes a few hours to days.

If the filter is now switched off only once for approx. 30 minutes, the bacteria continue to work until the dissolved amount of oxygen (O2) in the standing water is used up. If this occurs, the bacteria die off particularly quickly. This creates a chain reaction and the so-called nitrogen cycle begins to run backward. In this case, the non-toxic nitrate is converted back to the highly toxic nitrite when there is a lack of oxygen. Since the nitrite-degrading bacteria themselves cannot tolerate large amounts of this substance, the death process is accelerated. At some point there comes the time when the feed pump is switched on again, the mix of aggressive nitrite and billions of dead bacteria washes into the fish tank and the water quality is heavily polluted until the fish’s immune system fails at some point.

The filter is the heart of the pond and must be constantly supplied with food (fish excrement) and oxygen. Even if you have been practicing this for a long time and apparently do not see any problems, it is extremely stressful and harmful for all residents in the pond. In the long term, these disturbances lead to increased problems such as algae, diseases, and even total failure.

Myth number 7: Clearwater is healthy water

In principle, you can assume that pure optics only provide a little information about the nature of the water. The only information that can be deduced is that it is clear. Not more.

“Old hands” can sometimes quite easily deduce the state of the water from pure experience or observations. But only water tests can give precise statements. There are several variants of this. The strip test is probably the cheapest and easiest measurement method. Drop tests are much more accurate, but cost between 25 and 100 euros as a complete set. Mobile photometers are new to the market. These laboratory-like devices are currently the most precise method for checking all-important water parameters. They are available for around 300 euros.

Which one you choose has to be weighed up. Even if you treat yourself to the professional version, it is probably much cheaper than sick koi, which require extensive drug treatment by a specialist veterinarian, or algae that you have to combat with a cure, which can quickly cost over 200 euros (depending on the pond size). Even a single dead animal can hurt more than the luxury method of testing water quality. Many stationary specialist retailers offer water analyzes as a service, but they only represent a snapshot that you have to monitor continuously. So it is always worthwhile if you have the necessary measuring instruments available.

Myth number 8: There are enough vitamins in fish feed

You can recognize good pond food by its good packaging. It is airtight and, above all, does not let light through. Light and air are responsible for the fact that vitamins oxidize and are therefore no longer effectively available as nutrients. As soon as a transport packaging has been opened for the first time, this destructive process is activated inexorably. To compensate for this problem, a decent spray or good drops for revitaminating should be in every pond accessory cabinet. If you take a look around a good ornamental fish or pond department, you will often find a vitamin supplement on the counter because professionals know what is important.

Tests have shown that many diseases can be avoided with a boosted immune system. Especially the color development, mucous membrane thickness, and stress resistance in the case of water problems are enormously promoted. If stored in a cool place, the range is quite a few months, but at least one pond season. Even in spring, when the slowly rising water temperatures stimulate the metabolism of the fish, but also parasites become active, this measure is extremely important and can make the difference between a successful start and a failure. It is very easy to use: Either you dose the vitamin concentrates directly into the pond water so that they are absorbed through the gills and mucous membrane, or you put the necessary portion of food in a small container and drizzle or spray a little over the meal. A cure (3-4 times a week) is recommended in spring, in summer a weekly dose is sufficient.

Myth number 9: rainwater is harmless

Of course, rain that falls into the pond in the normal way is not a great risk. At least for the pond, whose water hardness is regularly checked and corrected. But you have probably already seen or read many times that many fish enthusiasts channel or collect rainwater directly into the pond via the gutter in order to carry out a partial water change. “In nature that is also rainwater!” Is the most common argument for it. But what happens to the raindrop on the detour through the rain gutter?

Even in the atmosphere, the drop picks up various dirt particles and soot. If it hits the garden shed canopy and runs down it, it washes any deposits from the roof that have previously formed. Perhaps there is a large fir tree right next to the garden shed, which also lets its needles fall onto the roof. In this way, the entire mixture of dirt particles and algae fertilizer is channeled into the pond in a concentrated manner. Rainwater is still particularly free of important minerals, which are, however, absolutely necessary so that the self-cleaning power of the water is retained. To compensate, you would have to continuously adjust the carbonate hardness, bind excess nutrients such as nitrate and phosphate with suitable preparations and eliminate heavy metals that have been loosened from the rain gutter and metal nails of the garden house canopy.

Pre-cleaned tap water is, therefore, more recommended. However, you also have to use a water conditioner here, but much less and less often.

Myth number 10: a filter for large ponds only

Medium-sized and small ponds in particular are often susceptible to fluctuations in water values. Although H2O becomes warm or cold more slowly than air, the high midday sun in summer can heat a shallow pond to over 30 ° C. At night, a fresh wind can do just the opposite. Since the population density in most ponds is also clearly too high, cleaning and filter systems are of great importance here in order to make the climate bearable for all residents. They repair the damage caused by environmental irritation.

In the case of natural ponds, i.e. bodies of water that have been artificially created but have a volume of more than 5,000 liters, have large low areas, and are generously planted, a filter system is not absolutely necessary – at least as long as there is no need for crystal clear water. It is important to ensure that only small fish species such as sticklebacks, minnows, bitterlings, and gudgeons are used. These get along well with the natural food supply of insects and algae and are robust, even in frosty months. Nevertheless, care should be taken to ensure adequate ventilation by means of circulating pumps or air stones.

Mary Allen

Written by Mary Allen

Hello, I'm Mary! I've cared for many pet species including dogs, cats, guinea pigs, fish, and bearded dragons. I also have ten pets of my own currently. I've written many topics in this space including how-tos, informational articles, care guides, breed guides, and more.

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