Foil pond

from Wikipedia, the free encyclopedia
A liner pond as an ornamental pond (pond liner on the left in the picture). The pond surface is covered with grids to keep water birds away or to protect small children from drowning (which is more obvious because of the barrier fence ).

A film pond is an artificial pond , the sealing of films (so-called pond liners ) or film-like coating materials is often made directly on the site of connected individual webs or the reaction components. The same materials or construction methods that are used for liner ponds are often used for swimming pools and pools , (watering) tubs in horticulture or for sealing flat roofs , balconies , parking decks and landfills . In general, pre-surface sealants on construction sector as railways referred and the term sheets for packaging materials used, but has for waterproofing of ponds, the term pond liner naturalized. Roof sealing sheets are occasionally offered as pond liners; these also contain flame retardants (fire retardants ) and higher levels of UV stabilizers , which are not necessary for use as (covered) pond liner or which dissolve in standing water.

Foil ponds are in contrast to hard-shell prefabricated pools and pond seals with clay or loam or pools made of concrete. Pond seals with clay or loam are at risk of leaking if plant roots grow through the sealing layer or if animals damage the bank; they are more likely to be used in natural ponds where there is an inflow and outflow. Concrete is not waterproof due to microcracks and capillary pores (see also waterproof concrete ) and must be sealed with mastic asphalt , underlay foils or added sealants.

history

Older concrete basin sealed with mastic asphalt in the Royal Botanic Gardens (Kew) , London

Water basins were initially made of stone and concrete , later sealed with pitch or mastic asphalt, and small garden ponds were made of fiberglass-reinforced plastics .

With the development and market launch of swimming ponds, from around 1975, more and more foil ponds were built and the production processes continuously improved. Advances in technology also resulted in increased environmental awareness in the 1980s and the associated increased sealing of landfills including seepage water collection.

Purposes

Foil ponds are used, for example, as

used material

Required properties

UV stability

The foils are exposed to solar radiation, which is why they must be particularly stable against high-energy ultraviolet radiation . UV rays often destroy plastics (reactive radicals arise , as a result of which the molecular chains of the polymers are cracked and broken). In the case of polyvinyl chloride , chlorine atoms are released, which would corrode and oxidize the material. As a countermeasure, UV stabilizers are added to plastics , which form compounds with these radicals (chlorine atoms). The UV radiation also reaches the film under water, since water is permeable to UV radiation .

elasticity

The preferred pond liners are those materials which are sufficiently elastic for the purpose of better processability and to be able to cling to the ground without cracking due to the water pressure. The type of film is usually chosen according to the substrate. Foil ponds that look like a swimming pool (built like this or as a repair to an older pool) can also be lined with harder foils and plastic parts as a seal. Soft foils or injection-molded plastic are used for irregular shapes

(Further) tear strength

If holes are formed (due to damage or an inhomogeneous composition, which usually occurs when using regenerated plastics), a hole should not tear further and not increase the damage.

Cold resistance

At lower temperatures, a pond liner should not become brittle , which could lead to breakage and leakage . Aged foils that have become brittle due to the loss of plasticizers (see below) can no longer be welded ; a complete replacement is then required. Such fractures usually occur in the difficult to avoid folds and bending loads (from pressure or ice pressure), especially if some materials have been exposed to sunlight for too long.

Slip resistance

Growing biofilms make most foils slippery, the rubber-like EPDM foils a little less. This is why extra pimple rubber mats are often laid on stairs and steps and handrails make entering / leaving swimming ponds safer.

Through biomineralization , mineral biominerals are excreted from the water over time. For example, chandelier algae or cyanobacteria ("blue algae") capable of photosynthesis precipitate calcium carbonate , the latter forming mat-shaped stromatolites in microbe mats . The microorganisms in the biofilms are then inactive at the base and die and continue to grow on the film surface. Diatoms ( diatoms ) precipitating silica from the water and form therefrom at normal temperature and normal pressure hydrous amorphous silicon dioxide . Alleged "limescale deposits" on the films therefore usually consist of homogeneous mixtures of calcium carbonate, mixed carbonates, apatite , silicon dioxide and silicates and are therefore difficult to dissolve even with acids.

Material thickness

The foils are produced in different thicknesses, often they are used in a thickness of about 1 mm. The foils should withstand the water pressure , which increases with depth . The following are published as guide values :

  • Thickness 0.5 - 0.8 mm for ponds with a depth of up to 80 cm.
  • Thickness 1.0 mm for ponds up to 120 cm deep.
  • Thickness of 1.0 - 1.5 mm for ponds with a depth of 150 cm.
  • Thickness of 1.5 - 2 mm for swimming ponds.

Basic materials used

Polyvinyl chloride (PVC)

Foils made of soft PVC are used for foil ponds

PVC film is a very inexpensive film because the raw material chlorine is an "inevitable by-product" in the manufacture of the most frequently used caustic soda . Among other things, the low price led to the boom in PVC products such as floor coverings, garden and camping furniture , pipes, window frames or PVC films.

Pond liners are usually put together with a hot air gun .

Another advantage of the construction of foil ponds is that (new) PVC foils can be easily welded . Even lay people and unskilled laborers can quickly learn how to join individual strips . The fact that hazardous chlorine vapors or dioxins , benzene , naphthalene , phosgene , toluene or xylene and phthalates escape (when working outdoors) are often ignored . In a study on exposure to hydrogen chloride and phthalate during hot gas welding of PVC foils on 72 construction sites outdoors, no occupational exposure limit values ​​were found, but such work in closed rooms (in other studies) did.

With the most frequently used hot gas welding , the strips are laid out, overlapped by 2–5 cm and homogeneously connected to one another using a hand welding device ( hot air blower ) and a pressure roller.

The frequent use and the good dyeability lead to a wide range of strengths and colors. They are usually available in thicknesses between half a millimeter and two millimeters, in colors mostly olive green , light green, blue, gray, black or beige .

The soft, flexible film hugs the surface and irregular shapes. Because wrinkles are unavoidable, the foil can be cut into pieces and individually adapted (for example in the case of stairs) (otherwise a concrete staircase is built on a foil).

The shelf life is around 10–15 years (less in pools with chlorinated water). Due to the addition of additives , the film is frost-resistant, but aged film can break (especially when wrinkled under the bending load ).

PVC film is heavier than water (the density varies between 1.20 and 1.35 g / cm³ depending on the plasticizer content.), PVC film sinks into water. In general, every pond liner of a (half) emptied pond can float if, in the course of a flood, an increased groundwater level pushes the then light liner upwards. Fermentation gases under the liner can also cause bulges when the pond is full if the pond was built on a former landfill.

Particular disadvantages of PVC are the disposal problems (see for example polyvinyl chloride # environmental aspects, disposal and recycling ), the high content of additives (see also polyvinyl chloride # additives ) and plasticizers , possible residual monomers ( vinyl chloride ), bisphenol A (as a stabilizer), as well as regenerated PVC (may contain additives that were previously allowed but now forbidden) and heavy metal compounds (as UV stabilizers ) and the migration of all these substances into the environment. See also plastic # environmental problems .

Cheap PVC films often contain phthalates as plasticizers (see also polyvinyl chloride # plasticizers ), nine of which are on the ECHA's list of substances of very high concern ( SVHC ). Environmental protection organizations criticize the fact that phthalates, especially DEHP, have been identified as carcinogenic, toxic to development and toxic to reproduction. Effects (in experimental animals) were mainly observed in the male offspring and manifested themselves, among other things, in reduced fertility and deformities of the genitals. The transfer of the findings to humans is difficult because the difference between relevant phthalate exposure (intake during pregnancy) and possible effects (e.g. infertility of the offspring) can often be decades apart. The Austrian Federal Environment Agency and the German Federal Environment Agency also warn against these plasticizers in films.

The non-chemically bound plasticizers, which can make up "up to 50% of the total mass", can be removed from a film, which also causes the film to become brittle after about 10 years. Broken PVC film in old film ponds and swimming pools is an indicator that the plasticizers originally contained have entered the environment through elution (leaching), migration (further migration into other plastics, solids or microorganisms) or evaporation. Plasticizers and additives can also migrate from the PVC into the plastics of the underlay nonwovens .

A phthalate-free plasticizer is, for example, PETV (pentaerythritol tetravalerate). For other alternatives, see.

Stabilizers are added to the raw PVC in order to increase the thermal stability during processing and to improve its resistance to weathering and aging . For this purpose, compounds such as stearates or carboxylates based on heavy metals such as lead , cadmium , tin , barium / zinc , calcium / zinc and calcium / aluminum / zinc such as cadmium stearate or lead stearate are used. (In the melting process, the metals, as "acid scavengers", catch the chlorine released and form metal chlorides). Cadmium compounds as stabilizers were banned by the EU in 2001, and lead stabilizers are to be replaced by 2015 (according to a source from 2010) (voluntary reduction target). Such metal-containing thermal stabilizers can be replaced by hydrotalcite (a magnesium-aluminum-hydroxycarbonate).

In addition, soft PVC can also contain antioxidants, heat stabilizers (support the shaping) such as organotin stabilizers and flame retardants (for example antimony trioxide ) as additives. Phthalates, bisphenol and the organotin compounds contained in PVC are considered to be endocrine (hormonally) effective, such substances influence the reproduction and survival rate of amphibians and even the reputation behavior of frogs "so specifically that all substances are classified according to their mechanisms of action and in environmentally relevant concentrations could be proven. " .

The most commonly used additives (phthalates, bisphenol A, organotin compounds, etc.) are only slightly soluble in water, but low concentrations arise in the water depending on their solubility . They are partially extracted again from the water by being adsorbed on contact with biogenic solids and then disposed of together with the pond sludge. Sucked off soil sludge is usually used as mulch for surface composting . The compost can then contain higher levels of plasticizers and other additives (bisphenol A, tributyltin ) than the water. The additives are out of the water extracts , the water can be used as solvent and extractant resume additives and further dissolved out of the film. This creates a (physical) equilibrium .

Synthetic rubber (EPDM)

Of the various synthetic rubbers, ethylene propylene diene rubber (EPDM) (see also EPDM sealing sheeting) is processed into pond liners.

EPDM foils are often pre-assembled as a whole piece and delivered to the construction site as a giant roll and then rolled out again. The membrane can also be installed at temperatures as low as −40 ° C (other materials are stiffer or break more easily, or sweat is more prone to errors in freezing temperatures), which makes the pond construction possible even in cooler seasons.

EPDM foils are mainly joined by vulcanization . For this purpose, the surface is first degreased and roughened with a primer and 2 foils are usually connected with an intermediate adhesive tape (which has evenly applied the necessary chemicals over the entire surface).

EPDM foils do not contain any plasticizers, but antioxidants and UV absorbers as additives.

The two fillers carbon black or chalk determine the few colors of the film: black or anthracite , light gray and white.

Modified polyolefin (FPO)

FPO, also known as TPO film (thermoplastic polyolefin), is a collective term for films made of polyethylene , polypropylene and their copolymers

Additives for polyethylene and polypropylene also include antioxidants, for example phosphites, phosphonites or thioethers.

Polyethylene

A distinction is made depending on the degree of crosslinking of the polymers and degree of hardness:

FPP film (polypropylene)

FPP stands for "flexible polypropylene", ie flexible polypropylene.

Sometimes FFP film is sold as "FPO film made of polypropylene". FPP film has a high strength, can not be glued, only welded.

Ethylene copolymer (isat) bitumen (ECB)

Mostly with centrally embedded glass fleece .

Double layer foils

In order to combine properties, thermoplastic materials are hot joined together, for example PVC + PVC (also for films made from regenerated materials), PVC with fused geotextile fleece , EPDM + PVC ("4EverFlex").

Coatings

Coatings are made with materials made from so-called liquid plastics or reactive resins . These are mixed on the construction site from resin components and hardeners (see also cross-linking ) in the coating lance and sprayed on or applied with the help of rollers (similar to paint). Protective clothing and a respirator must be worn.

Polyurea

Polyurea or polyurea is a plastic that results from a chemical reaction between an isocyanate compound and a polyamine reaction resin (similar to a two-component adhesive ) and hardens into a layer in seconds (!). In order to improve the watertightness, the approximately 3 mm thick covering is provided with a coating in a second coating process . Because substrates are pretreated with a primer as an adhesion promoter , a total of at least 3 spray processes are necessary.

fiber reinforced plastics

Glass fiber reinforced plastics and fiber reinforced plastics based on epoxy resin , polyester resin or acrylic resin are used.

The serious disadvantage of these resins is that they absorb water through osmosis and are poorly resistant to hydrolysis . In technical terms , such damage is referred to as "the pond has 'osmosis'". Watertightness can only be achieved by means of a topcoat. If this becomes brittle after a few years, water creeps underneath and lifts the surface layer off, the glass fiber fabric and the resins can get wet, but this can also happen beforehand due to soil moisture. Such damaged ponds can be re-sealed with polyurea.

Mastic asphalt and waterproofing slurry

Both are used for subsequent sealing of concrete basins (water collecting basins, cisterns etc.) and water basins in gardens (ornamental basins).

Bentonite foils (foils or nonwovens )

Bentonite foils or fleeces usually have a three-layer structure. A base layer of a geotextile is sodium bentonite or - calcium bentonite powder, or -  granules applied as swellable sealant. A cover layer (foil or fleece) is placed on top, all three layers are "needled" (sewn) together.

When water gets in, the embedded bentonite swells and clogs (with the help of the water pressure above it) the pores of the geotextile or those water passages that have formed due to (undesired) water runoff. A sufficiently thick compacted fine-grained soil layer may be necessary underneath.

If bentonite foil sheets are installed in an overlapping manner, the sheets are not welded, but the (approx. 0.5 m wide) overlapping strips are sprinkled with a layer of bentonite.

The simple and inexpensive way of laying has led to the fact that bentonite foils are increasingly being used for landfill or generally for floor sealing on large construction sites.

comparison

Properties (selection) of pond sealing materials
property PVC EPDM PE (HD) PE (LD) FPP Polyurea Bentonite foil
outstanding advantages
(examples)		 soft,
adapts to unevenness,
with fabric insert also root-resistant, several colors		 highly elastic (can also be processed in the cold), root-resistant, plasticizer-free, long guarantee periods Root-resistant, plasticizer-free, UV-stable root-proof, plasticizer-free, UV-stable; Roll width 6 m for large ponds Root-resistant, plasticizer-free, UV-stable highly flexible, root-resistant, for irregular pond shapes and shotcrete substrates, UV-stable, any color self-sealing
outstanding disadvantages
(examples)		 contains plasticizers, disposal problem, embrittlement in light above the water level only available in black (filler is carbon black ),
rarely gray or white		 Sheets (6 mm), only available in black harder film, only available in black harder film, only available in black expensive Sealing depending on the substrate and the load
Joining technology Hot gas
welding 		Vulcanization, bonding, transfer tapes Hot gas
welding 		Hot gas
welding 		Hot gas
welding 		spray on
Repair:
2K paint		 overlap

processing

Films are assembled at the construction site (see joining plastics ), light leaks can (colloquially "at the joints seam ask," although nothing sewn will) occur. The film webs are usually overlapped and joined together at the overlap by hot gas welding or gluing. The connection holds or seals the better the more the activated fiber molecule chains (by heat, glue or dissolving before vulcanization) are pressed together, not only in the melted state, but also during cooling .

PVC sheets can be bonded or (by means of Heizkeilverfahren , hot air (hot air welding) or cold / solvent welding agent THF ) weld . Rubber foils are vulcanized , welded (depending on the type) or glued with a special primer and adhesive or seam adhesive tape with seam sealing or hot melt adhesive , PE foils are also welded.

By cutting and joining the foils on the construction site, wrinkles in the material can be prevented; this production method requires more working time. If foils are pre - assembled by machine and delivered to the construction site as a whole and rolled out, creases cannot be avoided. Wrinkles then occur especially in corners, on stairs or in individual deep spots. Stairs or other fixtures such as islands or wooden frames are therefore often placed on top of the film in order to avoid creasing or costly cutting.

Large ponds and basins are increasingly being built with overlapped bentonite foils or other foils are assembled on site from (wider) foil strips.

To protect the liner from damage when cleaning garden ponds, special pond rakes are used, which do not tear the liner due to balls at the tips of the tines.

Foil color

The color of the foil (... or the coating) affects the appearance of the pond and the heating of the water. Floating algae give the pond water a light green color, adherent biofilms also result in a color change to green, offset mulm shades to gray-brown. Light colors (light ocher , light green) convey the color of clear sea or lake water in shore areas, light blue is reminiscent of swimming pools. On light surfaces, sunken leaves and settled mud are easy to see, which can be an advantage (you can better recognize the impurities that you want to remove) or a disadvantage (if there is stress to have to remove them). Sunk leaves and sludge can be cut off or removed with the help of a sludge vacuum , an impeller pump or a pond robot / service robot or a continuous suction system. Black foil heats the water faster, which can extend the bathing season, but also allow algae to thrive better. By introduced lime mortar , the color of the soil can be changed, round gravel or concrete slabs laid on it, or wood.

construction

The pond liner is aligned and the geotextile fleece underneath is clearly visible.
The pond liner has been laid.

Layer structure

In the case of foil ponds, several layers are usually laid, for example (starting from the bottom):

  • In the case of gravel floors, a layer of sand to level out unevenness, the sand does not have to be compacted, the water pressure takes care of that (therefore the edges of the film are only fixed when water has been let in)
  • a thin safety film, this is intended to protect the excavation against erosion during the construction phase after dredging and later to keep soil microbes or aggressive plant roots away from the pond film. Special root protection foils or rhizome barriers contain a thin layer of copper , which inhibits the tip growth of plant roots.
  • a protective fleece , usually made of polypropylene or polyester fibers, it serves as protection against roots and against sharp stones in the substructure that could damage the sealing foil. The fleece also distributes the pressure of the water column above it over a wider area and can bridge hollow spaces in stones.
  • occasionally a bentonite sheet. If a hole arises in the sealing foil, the bentonite gets wet, swells and clogs (with the help of the water pressure of the water column above) the integrated underlay of the bentonite foil or the nonwoven fabric underneath, so - called self - healing occurs.
  • the actual sealing foil
  • a coating of lime mortar as mechanical protection of the sealing foil or a coating for liquid plastic coverings to improve water tightness and for coloring
  • a lean (low-fertilizer) planting substrate in areas where plants are planted
  • Heaped round gravel to cover the foil and the plant substrate. Because of the poor UV stability (see also there ) of some foils (especially PVC), it is often recommended to cover the entire foil surface.

Laying a large film

If large foils are made up in a factory hall and joined with automatic welding machines (mobile devices), this large foil is delivered in one piece. To do this, the film is folded up like a folding fan and then rolled up. Depending on the size, the piece of film with a weight of> 150 kg must be precisely positioned on the construction site. Then the film is rolled out and the "fan" is expanded to its final size by pulling 4-5 strong people. By "billowing" the film, air is brought under the film, which reduces the friction on the floor and the film can be pulled further more easily. With enough time, a large film can be laid on by just one person

Bank design

raised capillary barrier at the edge of the pond
perfectly hidden capillary barrier (recognizable by the 3 large stones in the foreground)

On the bank, the foil is pulled up as a capillary barrier to prevent water from being sucked out of the pond by capillary effects in sand or soil. About 5 cm up excess film is covered with stones, kapillarbrechendem fine gravel or concrete grout or by vegetation (water side and outside the pond) or a bank of web camouflaged . This measure of the raised pond liner also prevents nutrient-rich surface water from being flushed into the pond and fertilizing the pond water during heavy rain events.

To maintain the uniform pond edge level , the future bank must be leveled before the pond is constructed . For this purpose, pegs (made of wood or aluminum) are hammered in along the contours of the future pond and the height of the future water level or the edge of the pond or reference marks (e.g. 40 cm above) are permanently marked on these using a ( laser ) leveling device. The height of the pond edge ( i.e. where the raised sealing foil ends) is often determined with a so-called bank tape , a strip made of stable, flexible plastic or aluminum. The bank tape is attached to the pegs and later the raised, overlapped sealing foil on the bank tape. Some (professional) pond builders only build the bank tape as a first construction measure or instead of a tape they lay a ( drainage ) pipe as a pond contour at the exact height. Other pond builders only assemble the bank band when the pond is almost full at the same time as the earthworks for the rest of the bank design. In any case, the sealing foil is only installed and an excess cut off when the pond is almost completely filled, because the weight of the water pulls the foil into its final position. In the case of cohesive ( clay ) soils, a drainage pipe is often buried outside the bank so that nutrient-containing surface water can be safely and quickly drained away in heavy rain and does not spill into the pond.

Often a plantable bank protection mat (made of polypropylene fabric, similar to a short-cut artificial turf mat) is attached on the water side . This serves primarily to the scoring , shearing and cutting action away from floating thin sheets of ice during winter from the seal film to hold as a base for (seeded) plants and to UV-light from PVC film. Pocket mats attached to the bank and hanging almost vertically in the water allow the use of plants with root mass on the water-side bank and to camouflage visible foil. Composite mats (made of PVC) are placed on sealing foils and serve as a claw-capable subsurface when all floors and walls are to be lined and protected with mortar.

Instead of the shore protection mat, pond bags filled with gravel are stacked against the dangers of the ice (these are mostly sandbags made of UV-resistant, frost-resistant polypropylene fabric ).

The rhizome (with stalk) of the bamboo species Phyllostachys reticulata

On the bank under the sealing foil, “Bibergitter” (mats) are sometimes laid or fiber-reinforced concrete is sprayed on to prevent voles , moles , mice , muskrats , beavers or plant roots from perforating the sealing foil . 2 mm thick PE foil is also suitable for holding of rodents to allow the aggressive and hard shoot tips of bamboo - rhizomes have been excluded.

The design of the pond bank and the pond depth (as with any pond) have an impact on whether children or adults who accidentally fall into it can save themselves on their own. Steep banks can become very slippery due to the build-up of biofilm on the foils and make it impossible to get out. But even animals that have fallen into it (such as hedgehogs or mice ) can drown if the bank is built too steep or everything is surrounded by high ashlar stones.

Internals

Sometimes walls or rectangular concrete pools are set up in the construction pit to reach vertical walls like a swimming pool or to create a regeneration zone all around in swimming ponds . In most cases, a stable concrete floor slab is poured for this. If such a basin is provided under the foil, the foil is visible on the vertical walls when the water is clear, but if the basin is placed in the foil-lined pit, the foil can be covered everywhere and the pool walls can also be plastered or tiled , the floor can be clad with sand, roll gravel, concrete slabs, stone slabs or wooden boards or the pool is built from solid wooden planks . Otherwise, no concrete is required under the foil, the ice pressure of the expanding ice in winter is opposed to the ice pressure of the frozen ground as an abutment .

For wooden fixtures that are constantly in the water, freshly felled "green" (undried) resin-poor fir wood is used, for ladders with water / air alternation, more durable hardwoods such as oak or robinia wood (which, however , would release tannins and humic substances into the water if used over a large area which can cause the water to turn slightly brown). Ladders and handrails at steps are also often made of stainless steel , although rusting iron (through the formation of iron phosphates ) could help to separate phosphorus from the water in order to limit the growth of algae (see also phosphorus elimination and phosphate trap ).

In many cases, underwater spotlights are also installed, as in swimming pools with low voltage (220/230 V) or low voltage . Pond liners are electrical insulating materials , therefore, there is no ground for operation with built-in within the film pond pump and lamps in low voltage, therefore, when damaged cables, it is applied to a residual-current device to any fault current detection. Only diving into the water with your hand or a net can lead to a current drain and then to the death of the person concerned. Earthing (which must be checked by a specialist), via which a fault current could flow, can be established via a stainless steel pool ladder or via an extra earthing rod.

The same "swimming pool linings" (polyester-reinforced foils based on PVC or FPO) to achieve a stone decor or tile decor look are also used in the design of pool-like foil ponds instead of built-in stones or real tiles.

Pumps and pipelines

When pipes to externally located pumps and filter stations or lighting fixtures penetrate the film, an exact seal is created using silicone with simultaneous contact pressure. In order to avoid leakages near the ground, such penetrations are made near the water surface, which simplifies later repairs. Often, instead of penetrations, the bank is perforated in a U-shape and the necessary pumps are located in the connected trench, which then has the same pond seal. The pumps usually lift the water into a basin with a higher water level, from which the water flows back into the pond on a slope (and possibly after passing through water filters).

In the case of supply pipes and hoses and lines from and to circulating water pumps, the largest possible diameter of the lines has advantages. The volume flow is dependent on the fourth power of the radius (due to the Hagen-Poiseuille law ). For example, reducing the pipe diameter by half would increase the flow resistance 16 times or increasing the pipe diameter by three times (one and a half inches instead of half an inch) the volume flow by 81 times. Increasing the pipe diameter can therefore increase the pumping capacity of a pump (with the effect of a greater pumping height or more flow), which means that weaker pumps can be selected, which significantly reduces energy costs.

Aquarium window

If foil ponds are used for nature observation or as fish ponds, windows are occasionally built into the wall. For this purpose, concrete walls with window openings are provided, into which water pressure-resistant polycarbonate panels of the appropriate thickness are mounted. The sealing to the pond liner is done with the help of sealing silicone and screw connections. Kits are now available for this. With aquarium windows, daylight can cause annoying reflections due to total reflection.

ecology

Due to the lack of a connection to the surrounding soil, which could serve as a habitat and "supplier", and due to the mostly lacking inflow, the number and variety of living beings in the water and in the soil zone ( benthos ) is limited. Living organisms or nutrients practically only come into the biotope of the foil pond through water birds flying in (traveling in wet plumage or from their excrement) or through entry with the wind or through biomass (fallen leaves, pollen, dust, dirt etc.) . Only dragonflies that prefer stagnant water will soon set in by themselves, their predatory larvae soon decimate mosquito larvae and amphibian spawn .

That is why it is often recommended to "inoculate" the liner pond water with water from running waters or other ponds, soil extracts, cultured (more or less effective) microorganisms such as beneficial bacteria at different times of the year . The aim is to achieve a stable, varied biological balance between phytoplankton (algae) and algae-consuming zooplankton ( e.g. copepods , tardigrades , rotifers , diatoms , roundworms and bacterial populations ) more quickly . So amphibians or water snails can spawn into the pond water (water snails, for example, eat algae from foil or stone surfaces).

In the case of liner ponds that are used as bathing water, the aim is to remove the dissolved nutrients from the water that were brought in with the fill water or by the user, as otherwise algae cloud the water and float on the surface as algae carpets or algal blooms . This is often done by netting the algae, removing submerged leaves and sediment or "harvesting" swamp and water plants or, in the case of more technically complex variants, with the help of water filters .

A net stretched over the pond in the autumn before the leaves fall can prevent the entry of large masses of fallen leaves, which could be leached or decomposed over the winter and thus bring in large amounts of soluble nutrients. Remains Fall foliage at the bottom of the pond, so silted up as a pond, more and more, with associated negative side effects ( putrefaction gases that rise from the bottom of the pond, the water is the nutrient rich "soup" with excessive growth of algae ( eutrophication ), " upset by lack of oxygen."; U a m..)

Barley straw in jute sacks hung in the pond water is often recommended as a home remedy to combat filamentous algae, in fact, it provides the aqueous extract of soluble organic substances for anaerobic denitrification are needed. With denitrification, nitrates are reduced to gaseous nitrogen (which bubbles out into the atmosphere) and thus removed from the water. This removes an important nutrient from algae. A similar effect is achieved with soaked sacks of (pre-washed) peat, which releases humic substances into the water, lowers the pH value (which is not beneficial for a certain algae) and can turn the water brown (a brown color can also be caused by entry and longer Lingering in the water caused by dry walnut or horse chestnut leaves ). Horticultural peat may be contaminated with fertilized soil (packed with the same machine), while aquarium peat is cleaner.

Photo gallery

  • Pond liner in a self-cleaning swimming pond (without pumps)

  • Lined pond liner

  • Pond liner in a small garden pond. Usually it is avoided that the film remains visible. Pond banks should be designed in such a way that animals ( hedgehogs etc.) that have fallen into it can leave it safely.

literature

Web links

Remarks

  1. ↑ more flame retardant roofing membranes containing According to another source (ISGATEC) it would be difficult to equip EPDM flame retardant, as flame retardant plasticizers ausschwitzten at higher doses in EPDM.
  2. ↑ a b seldom in German-speaking countries, more likely in English-speaking countries than "EPDM Rubber white"

Individual evidence

  1. ↑ High polymer sheets for waterproofing in the building sector. A compilation of high polymer roof u. Sealing membranes, their properties and possible uses; Copy of the final report of a research project funded by the Federal Ministry of Transport, Building and Housing -BMVBW-; Institute for Building with Plastics eV; "On behalf of the Federal Minister for Regional Planning, Building and Urban Development, 5300 Bonn"; As of March 1983 (2nd edition); Building research, inventory number 1895; Copy published by Fraunhofer IRB Verlag (PDF file)
  2. ↑ Garden - The Green by GU. P. 162 ( limited preview in Google Book search)., Last accessed in February 2020
  3. ↑ Richard Weixler: garden and swimming ponds: construction - planting - care ; Stocker Verlag, 2008
  4. ↑ The right thickness of the pond liner, at gartenteich-info.de
  5. ↑ a b c Create and design garden ponds. P. 12 ( limited preview in Google Book search), last accessed in February 2020
  6. ↑ a b Underestimated dangers in plastics processing. Vapors hazardous to health from plastic welding / cutting. ; Information sheet from the Unfallkasse Nordrhein-Westfalen; at unfallkasse-nrw.de (PDF file)
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  12. ^ A b c Holger M. Koch, Tobias Weiß, Thomas Brüning: Substitution effects in phthalates. Human Biomonitoring Examines Exposure To Plasticizers ; IPA Journal; 03/2015; (PDF file) ; at dguv.de (German statutory accident insurance)
  13. ↑ PVC - Harmful plasticizers ; at global2000.at, last accessed in February 2020
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  15. ↑ a b PHTHALATE, the useful plasticizer with undesirable properties (PDF file) ; (German) Federal Environment Agency for Humans and Nature, last accessed in February 2020
  16. ↑ Ansilla Frank, Marc garlic, Benjamin Sandoz; Technology study for processing polyvinyl chloride (PVC) ; Fraunhofer Institute for Chemical Technology; Pfinztal; 2005; Page 4 (PDF file) , last accessed in February 2020
  17. ↑ Clare Goldsberry: FDA approves non-phthalate PVC plasticizer Pevalen for food-contact applications ; Packaging Consumer Products, Extrusion: Film & Sheet, Materials, May 28, 2019; newsletter at plasticstoday.com
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  19. ↑ General report on treatment and recovery routes for PVC waste ; Federal Ministry of Agriculture, Forestry, Environment and Water Management, Vienna, December, 2002 (PDF file) , last accessed in February 2020
  20. ↑ a b Hans Jürgen Wernicke and Joachim Großmann: “Environmentally friendly stabilization of PVC by synthetic hydrotalcites” ; Current newsreel of the GDCh; 2008, last accessed February 2020
  21. ^ Vinyl 2010. Voluntary commitment by the PVC industry. The European Council of Vinyl Manufacturers (industry association) (PDF file) , last accessed in February 2020
  22. ↑ a b TBT - Organotin Compounds - A Scientific Inventory. Berlin, 2003, Federal Environment Agency Berlin, (PDF file)
  23. ^ André Leisewitz, Hermann Kruse, Engelbert Schramm: Development of assessment bases for the substitution of environmentally relevant flame retardants ; Research report 204 08 542 (old) 297 44 542 (new), Environmental Research Plan of the Federal Minister for the Environment, Nature Conservation and Nuclear Safety, December, 2000 (PDF file) , last accessed in February 2020
  24. ↑ a b c d e f P.Pfluger, B. Wasserrab, E. O'Brien, A.Prietz, P. Spengler, C.Schneider, A. Heussner, T.Schmid, B.Knörzer, JWMetzger, DRDietrich: Development and validation of in vitro test systems for the detection of endocrine disrupting foreign substances: chemical-analytical examination and biological proof of potentially endocrine disrupting substances in sewage treatment plant outlets or receiving waters ; Environment and its safety as a basis for life (BWPLUS); at pudi.lubw.de (State Agency for the Environment Baden-Württemberg); (PDF file) ;
  25. ↑ W.Kloas, C.Bögi, A.Gaete, O.Jagnytsch, A.Krüger, G.Levy, C.Lorenz, N.Neumann, R.Opitz, C.Pietsch, W.Schumacher, A.Tillack, A .Trubiroha, R.Urbatzka, C.Van Ballegooy, C.Wiedemann, S.Würtz, I.Lutz: Test procedure in amphibians for the detection of endocrine disruptors (ED) with effects on reproduction and the thyroid system ; in: Umweltbundesamt (Ed.): Proceedings 3rd status seminar Chemicals in the environment with an effect on the endocrine system. Scientific foundations of evaluation and regulation, Berlin, 2005; ISBN 3-8167-6968-3 , page 38; (PDF file)
  26. ↑ Frauke Hoffmann, Werner Kloas: Suitability of the reputation behavior of the clawed frog as an end point for recording the effects of hormonally acting substances on aquatic ecosystems ; Environmental research plan of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety; On behalf of the Federal Environment Agency; April, 2016, (PDF file)
  27. ↑ Peter Grathwohl: Sorption and desorption of hydrophobic organic pollutants in aquifer material and sediments ; in Jörg Matschullat, Heinz Jürgen Tobschall, Hans-Jürgen Voigt, et.al .: Geochemistry and Environment. Relevant processes in the atmosphere, pedosphere and hydrosphere
  28. ^ Robert Sattelberger, Marianne Heinrich, Gundi Lorbeer, Sigrid Scharf: Organotin compounds in the aquatic environment ; Publication of the Federal Environment Agency Vienna, 2002, ISBN 3-85457-661-7 ; (PDF file)
  29. ↑ Company website of an additive manufacturer , last accessed in February 2020
  30. ↑ a b Material compass - EPDM - all-rounder with tight failure tolerances ; at isgatec.com
  31. ↑ a b c d e Handbook of Water in the Garden. ( limited preview in Google Book Search), last accessed in February 2020
  32. ↑ a b Antioxidants Stabilizers Selection for Polyolefins (PP, PE) , website of an additive manufacturer, last accessed in February 2020
  33. ↑ Dopico-García, López-Vilariñó, Gonzalez-Rodríguez: Antioxidant content of and migration from commercial polyethylene, polypropylene, and polyvinyl chloride packages. ; J Agric Food Chem. 2007 Apr 18; 55 (8): 3225-31. Epub 2007 Mar 24, last accessed February 2020
  34. ↑ a b V. Ambrogi, (...) V. Marturano: Additives in Polymers , Modification of Polymer Properties, 2017.
  35. ↑ Lining Systems ; Company website of a film manufacturer, last accessed in February 2020
  36. ↑ a b c Robert Jungnischke: The pros and cons of GRP in koi pond construction ; website of an expert for GRP seals, last accessed in February 2020
  37. ↑ Konrad Bergmeister: Concrete Calendar 2019 - Focus. ISBN 978-3-433-60934-7 , p. 837 ( limited preview in Google book search).
  38. ↑ garden ponds. P. 8 ( limited preview in Google Book Search), last accessed in February 2020
  39. ↑ Ulrike Witz: Fixed bed nitrification and denitrification with solid carbon sources ; Wuppertal, 2005 PDF file

See also