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Whether peat is used for filtering depends primarily on which fish are being kept, e.g. For example, a number of South American tetras and dwarf cichlids like soft water rich in humic substances.
Peat acts as a weakly acidic cation exchanger. Peat removes the hardeners bound to bicarbonate and in this way virtually eliminates carbonate hardness. At the same time, the overall hardness is reduced.
Commercially available garden peat has a capacity of about 300 liters of hardness. 1 liter of peat reduces the carbonate hardness, e.g. B. 30 liters of water by 10 degrees of hardness. The pH is then about 3.
With the help of peat, the pH can be acidified to very low levels that are difficult to achieve with other methods. Due to the ion exchange capacity, a stable pH value is achieved, which prevents an acid drop even with a carbonate hardness of 0.
The exchange capacity, together with the contained humic acids, which are gradually released from the peat, leads to various positive effects:
Arguments for peat:
- Peat lowers carbonate hardness.
- Peat lowers the pH.
- Peat buffers the pH.
- Peat has an antibacterial effect.
- Peat has an antifungal effect.
- Peat prevents spawn fungus.
- Peat protects the mucous membrane of the fish.
- Peat has an anti-algae effect.
- Fibrous peat is suitable as a spawning substrate, e.g. B. for killifish.
- Peat has a positive effect on fish physiology.
- Peat improves plant growth.
Arguments against peat:
- Peat degrades plant growth.
The occasionally observed positive effect on plants is probably due to the fact that humic substances are natural chelators. They keep plant nutrients such as iron in solution, making them available to the plants.
On the other hand, the darkening caused by the color of the water can lead to growth problems in light-hungry plants. Too low pH values, e.g. B. below 5, can lead to growth problems.
How peat is used
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Peat filtering should be carried out outside the aquarium if possible. The most effective means of blackwater production, peat and alder suppositories, also have the greatest side effects, as they can cause increases in nitrate and phosphate levels.
Peat consists of plants that have only partially decomposed. The decomposition process was interrupted by the conditions in the bog. With longer use in the aquarium, the mineralization interrupted in the peat bog starts again and nitrate is formed. Depending on the peat, mineralization can start after days or weeks.
If the water is treated outside the aquarium, it is usually only filtered over peat for a few hours or 1 to 2 days. Nitrate or phosphate is therefore not newly created. Only the nitrate or phosphate that is already mineralized in the peat can be washed out. This amount also varies depending on the peat, so it needs to be tested.
Some aquarists change the peat less often without problems, e.g. B. only every 3 months. Here, too, you have to gain your own experience.
In the case of continuous processing, the water is passed briefly over the peat. Alternatively, peat and water are placed in the same container and mixed by stirring.
A permeable bag or nylon stocking with peat is placed or hung in a container with water. Loose peat makes the water cloudy with fine suspended matter. Although the particles settle on the floor after a while, they quickly whirl up again when touched lightly.
The water is circulated with a pump. If necessary, a timer can start and stop the circulation several times a day.
An aquarium filter can also be used as a pump. The peat can also be filled directly into the filter pot. Of course, peat can also be added to the water tank.
If the water is removed from the filter outlet when filling the aquarium, the filter can also be used to filter out small peat particles with filter floss. For this purpose, a plastic grid is inserted into a filter bowl. Such grids or alternatively insert baskets are available for practically all filter types. Fine filter floss or cotton cosmetic floss is placed on the grid or in the basket. The peat is wrapped in a nylon stocking or in a gauze cloth with a mesh size of 100 µm and placed in the filter bowl. The peat can be pressed a little because it collapses when it gets wet. The filling may have to be adjusted to the filter type and the direction of the water flow.
Even when used in the aquarium, peat can either be filled into the filter or hung in a bag in the aquarium. If two separate filter bags are used, the bags can be replaced alternately to achieve a more even effect. The use in the internal filter is usually problematic, since part of the filter content usually leaks into the aquarium during cleaning or when changing the peat.
Another option is to run the water from an osmosis system directly over peat if the filter pot has an outlet at the bottom. A U-tube is attached to the spout in such a way that it bends just below the top edge of the pot.
The water drips from the osmosis system into the filter bowl, which is filled as described above. The pot is always filled with water thanks to the U-tube. The water slowly seeps through the peat.
Depending on the peat, it lasts a very long time. According to one report, filling a medium-sized filter pot produces at least 200 liters of water with a pH of 6 to 6.2.
If the water flows too fast, fine peat particles are carried away and the water becomes cloudy.
How much peat is needed?
Peat is a natural product. It is therefore not possible to foresee which exchange and buffering capacity the respective variety has and which carbonate hardness or which pH value will be achieved with it. Therefore, own tests with peat types and quantities must be carried out.
The effect of a peat ball is the same. There may be differences with a new peat ball of the same type. Most of the time, however, these differences are small. Significant differences can occur between different types of peat, such as black peat, white peat, raised bog peat, fen peat, etc.
Which peat is suitable
The peat does not have to be bought in expensive pet shops. Peat from garden supplies is also suitable. The peat used must not be fertilized. Suitable is z. B. Flora Torfboy (Floratorf), a white peat. It is unfertilized, acidifies well and is available in hardware stores. Raiffeisen markets also sell suitable peat.
Peat and pH
Fulvic acids contained in peat falsify the results of drop tests for pH measurement because they color the water. Depending on the amount of fulvic acids, the water changes color from light yellow to strong brown. Drop tests, for their part, indicate the pH value by discoloration, which can also be in the yellow to brown range, depending on the test and measuring range. For this reason, some pH tests come with a so-called comparator block, which compensates for the natural color of the water.
The same applies to the CO2 content, which is correlated with the pH value. Drop tests for CO2 actually measure pH and are therefore also affected by peat discoloration of the water.
It makes sense to purchase a pH meter. As soon as the carbonate hardness is no longer used as a buffer, ie the carbonate hardness is close to 0, the pH value can drop very quickly with further filtering through peat. In extreme cases, an acid fall can occur.
The humic acids introduced with the peat in turn form a buffer against changes in the pH value. The lime-carbonic acid buffer is replaced by a peat buffer. The aquarium can be operated with a carbonate hardness of 0. In addition, there is the buffering effect of the filter sludge, especially with the mat filter. If there is a lot of sludge, ie a high buffer effect, the pH value may hardly change when the first peat is added.
Since the humic substances are slowly broken down, the pH value also slowly rises again. If the water is changed weekly with peat-filtered water, a stable pH value will be established over time. Peat buffers to a lower pH than the lime-carbonic acid buffer. Depending on the type of peat and the conditions in the aquarium, the pH can range from 4.5 to 7 in soft water.
Two simultaneously acting buffer systems in the aquarium overlap and the pH value results from the concentration ratio of both buffer systems. When the carbonate hardness is high, the lime-carbonic acid buffer regulates the pH value and peat practically does not lower the pH value. Very large amounts of peat would be required to noticeably lower the pH. This would lead to a high concentration of humic substances that most fish can no longer tolerate. So that the pH value can be noticeably lowered with peat, a low carbonate hardness is necessary. The carbonate hardness should be determined by other means, e.g. B. an osmosis system, can be reduced to values below 3 to 4. In this case, the peat buffer regulates the pH. The lower the pH value should be, the lower the previously set carbonate hardness must be. How far the pH drops depends on the type of peat.
The lowering of the carbonate hardness by peat therefore depends on the capacity of the peat and on the carbonate hardness. The humic acids in the peat slightly acidify the water. Peat does not replace an osmosis system but supports it and keeps the pH stable.
Since the strength of the individual effects cannot be given in general terms, it makes sense to take regular and reliable measurements with a pH meter at the beginning and to carry out control checks from time to time.
peat granules
Various manufacturers offer peat granules for aquaristics. The granules have the advantage that the aquarium water is not clouded.
However, granules acidify the water less and the costs are significantly higher than peat. Some types of granules can lead to increased levels of phosphate, nitrate, ammonium and ammonia. The already mentioned white peat from the nursery acidifies more and does not increase the values mentioned. However, peat from the nursery can initially cloud the water more than granulate.
Peat granules should also be renewed after about 2 weeks.
Prolonged use may result in brush algae, according to reports. As with peat, the water can also be treated with peat granules before use in the aquarium. The easiest way is to fill a filter with peat or peat granules and filter the water over it.
alternatives
If the carbonate hardness is to be lowered with peat extract, the extract must contain mineral acid, e.g. B. hydrochloric, sulfuric or phosphoric acid. Because humic acids are poorly soluble in water, no noticeable softening is achieved with them alone.
As an alternative, osmosis systems or ion exchangers come into question, which reduce the water hardness. The pH value is also lowered in this way. If the carbonate hardness is halved, the pH value decreases…