Wetland Pools

FREQUENTLY ASKED QUESTIONS

Where does the idea for a wetlandPOOL come from?

One of the founders of permaculture, Bill Mollison described the idea of a naturally cleaning pool in his book Permaculture, a Designers Handbook. The idea was developed in the 1980's in Austria, and has spread since.

The wetlandPOOL follows the principles of a permaculture project in that it works with nature, instead of against it. Processes that occur naturally are used to purify water and create a clean swimming pool. The wetlandPOOL continues to function with minimal human intervention, and the pool ecosystem becomes a part of a broader ecosystem.

We try to take the principles of permaculture further in the designs of our pools by including aeration and the need for a skimmer, both necessary inclusions, into the design.

Is a wetlandPOOL good for the environment?

We are living in a time when we are beginning to see the damage as a result of our interventions in the natural world, and all of us are questioning our direct impact on the environment.

A wetland pool, if well designed, will use less electricity than a conventional pool. It uses about the same amount of water as a conventional pool; and most importantly, it uses no chemicals. It therefore does not pollute your immediate household environment, your garden, your family, your neighbours or your pets. The chemicals used in a traditional pool have an energy production component in manufacturing, packaging and transporting. A wetland pool is less work than a normal pool and involves fewer trips to a pool shop or supplier of chemicals, and has a smaller energy footprint than a conventional pool.

When we look at our immediate home environments, the presence of a large body of fresh drinking water in our gardens becomes a big plus. Pets can drink the pool water; birds queue up particularly in the dry months to drink from and bath in the water. The water is clean enough for frogs and fish to live in it if you want them, and the sound of constantly flowing water is very soothing.

A wetlandPOOL works with nature and naturally occurring processes to clean the pool water and maintain a healthy system. This is in contrast to the chemical battle against natural processes with a more traditional chlorine or salt water chlorinated pool.

The way forward with swimming pools in an environmentally conscious society is with a wetlandPOOL.

What plants are planted in a wetlandPOOL?

The wetland is planted with four primary types of plants, each of which serve an essential function; deep water plants, shallow water plants , water lilies and oxygenators.

The deep water plants, such as papyrus and bullrushes, grow fast and rapidly create organic mass as they grow, storing away nutrients that enter the water. These plants have large root bowls, and the surface area of the roots is the most active area of the filter. They also shade the water, which helps prevents the buildup of algae in the wetland.

Shallow water plants, or marginals, are any of a large variety of species that grow in shallow water or completely out of the water with only their roots immersed. These plants add variety to the absorption of nutrients. Different plants have different chemical requirements and if the pool was dominated by only a few species there could be a build up of certain nutrients or salts that those plants don't need, and hence the need for more varieties of marginal plants. Marginal plants also absorb nutrients from shallower water than the deep water plants do. As with the deep water plants they shade the water, their roots filter the water and the roots also increase the surface area of biological filter.

Water lilies primarily create a pond microclimate under their leaves for zooplankton, one of the main feeders of water borne algae. After a few years the lilies extensively shade the open water. We have found that by combining water lilies with cape pondweed (waterblommetjies) you can get year round growth and flowers, as the cape pondweed is more active in the winter, and the water lilies are more active in the summer.

Oxygenating plants are submerged plants growing either in suspension in the water such as hornwort (ceratophyllum demersium) or attached into the gravel such as eel grass (vallisnaria spiralis). These plants compete directly with the algae for water borne nutrients, and the more dense the planting, the less algae in the pool. We find it takes usually about a year for a sufficiently dense growth of oxygenators to establish following the introduction of a few hundred plants. Some people refer to oxygenators as fish tank plants, as they work in the wetland pool in much the same way they do in a fish tank, giving clarity to the water. Oxygenators are called oxygenators as they dissolve oxygen in the water during photosynthesis.

To plant indigenous or not indigenous?

We are based in Southern Africa, and plant mostly wetlands that are of entirely Southern African indigenous plants. To plant a pool entirely locally indigenous to any specific plant region is very difficult, mainly because the supply of water plants is very limited. We are currently dependent on wholesale nurseries for our supplies of plants, and they grow for a market that isn't looking for such a large range of plant species as we are. With time we believe that wetlandPOOLS will increase the demand for locally indigenous wetland plants to the extent that they will be more profitable for the suppliers, and more species will be grown. We are currently (July 2010) working on a pool that is to be entirely locally indigenous to the fynbos of the Westtern Cape.

Trees?

We are now gowing a few tree species in our pools and wetland. We have had success with fever trees (acacia xanthophloea), ouhout (leucosidea sericea) and the safsaf willow (salix mucronata). There are tricks to planting and containing them, so don't just rush out and drop a tree in your pool!

What about animal life?

Your wetland pool will attract more animal life to your garden. Birds are usually the first to find the pool and will become a regular feature, especially in the dry season. Many birds need to drink fresh water daily and they will be there particularly in the mornings and the evenings. Birds prefer a shallow waterfall for drinking and bathing, so deliberately including one in the design in an easily visible spot is a good idea.

Fish will have no problem living in your pool, and it is up to you to decide whether or not you want them. There is a price to pay with having fish. They will increase the amount of string algae in your pool and wetland, and so we recommend that you don't add them.

Any frogs or toads in your neighborhood will converge on your pool. This is the greatest of compliments to your water quality with frogs being on the decline worldwide. However some frogs do produce a degree of noise, especially at night, and to some this can be a flip side. If and when they appear, you can decide on how noisy they are and then decide whether to leave them be or to capture them and relocate them to some nearby natural wetland. We always try to make sure that there is a frog ladder or easily accessable point in the wetland so that frogs can easily climb in and out of the pool.

Insects are also an integral part of the pool life. Water gliders will stake out their territories across the surface of your wetland, and dragon and damsel flies will hover overhead. Their larvae will live as predators to other insects in the wetland and they will all be part of a self regulating eco system.

With time we hope to tie in with the endangered frogs breeding scheme, and your wetland pool can then be a captive breeding colony for an endangered frog species.

wetlandPOOLS create a tranquil home for wildlife.

Does a wetlandPOOL contain algae?

All wetlandPOOLS contain algae. Algae growth shows that the pool is alive and healthy. There are generally two different types of algae that will grow in the pool.

Free floating algae is microscopic unicellular algae that lives in water and feeds on nutrients floating in the water. The free floating algae is what gives some ponds or dams their characteristic green colouring. In a wetlandPOOL this algae is rarely an issue as the filter removes it from the pool.

String algae is ever present in the pool. All surfaces in the pool develop at least a patina of string algae. There are many different types of string algae, and almost every environment in your pool will have an algae that will specialize in growing there. As water salinity, pH, tempreature or disolved solids content changes, so different string algaes will come and go.

There are a number of ways that the growth of string algae is curtailed. This is primarily through the presence of a good functioning, mature wetland filter, a large numbers of oxygenating plants, the reduction of light available for the algae, and if it becomes excessive, the physical removal of the algae.

How much work is looking after a wetlandPOOL?

Looking after a wetland pool is an exercise in gardening.

Once a week the pool weir needs to be cleared out to remove leaves or other debris that have fallen into the pool. If there are no obvious sources of debris then we would suggest removing the barrier of the weir and just allowing debris to enter the wetland and be processed by the filter. If you go away for a while this is also a good idea as if the weir becomes blocked the pool could overflow.

If you have an automatic top up for the pool - which is recommended - then the water level will maintain itself, but if not you need to make sure that the water level in the wetland doesn't get too low, and a small weekly top-up may be necessary. Rain water or borehole water can be used for refilling, but grey water is not recommended.

Depending on the size of the pool, its location and the amount of dust in the air, the bottom of the pool will need to be vacuumed about once every month when you are swimming in it. If you are not swimming in the pool, the dust can remain unless you find it unsightly. We usually recommend vacuuming with a separate submersible pump attached to a conventional pool vacuum hose with a leaf catcher on the hose. The vacuumed water is usually dumped strait into the wetland. With pools that have a continuous water surface between the pool and wetland, the vacuumed water needs to be filtered through a conventional sand filter or a spa dust filter to remove the dust. The whole vacuuming exercise generally takes about half an hour. An automatic pool cleaner can also be used, but it needs to be designed to acommodate this.

Plants need to be pruned once a year, but you can prune off dead leaves or stems whenever necessary, as with a normal garden. Once a year, normally in winter or autumn (before the water temperature gets too chilly), you need to wade into the wetland with a pair of secateurs and dramatically cut back all the plants. Water lilies don't need cutting as they rarely get so dominant as to be overgrown, so just remove their dead leaves or flowers if they become unsightly. The oxygenators seem to self regulate, so we don't recommend the removal of oxygenators. We often will harvest excessive oxygenators from existing pools to start up new pools. Generally the more oxygenators the better. You should try to keep an eye on maintaining the variety of plants in the pool, and as with a normal garden, if you find an odd water plant in a nursery that you'd like to try out, give it a go.

The wetland of a pool will very gradually silt up, primarily as a result of dust or inorganic material that enters the pool. It seems likely that this will be a problem after about 15 years, which is the European experience. Once this has happenes, the wetland is drained, the plants are removed, the gravel is washed and the plants are then replanted.

The maintenance of the pool doesn't require water testing, doesn't require harmful chemicals and doesn't involve much time at all.

How is the wetland like a garden?

Your wetland will become a part of your garden. Obviously insecticides and fertilizers must not be added to the pool, and storm water run-off should be kept out of the pool. If plants die they must be removed from the pool, and should be replaced. Any plant that is happy to grow in water can be planted in the wetland and will enhance the pool. In winter the wetland needs to be cut back dramatically, and in summer the wetland plants quickly fill the gaps opened up.

We have had requests for pools with specific colours, for local indigenous plants only, and for as many edible plants as possible. The number of options of choices are as varied as there are ideas to go around.

Water garden

Does a wetlandPOOL use less water?

No, a wetland pool does not use less water than a normal pool, it probably uses about the same amount. The water lost through evaporation in a wetland pool is greater than for a conventional pool as there is generally a larger surface area, and the plants transpire and so lose more water than a conventional pool through evaporation. However, no backwashing of filters is required as with a normal pool, as organic particles are processed and removed from the filter through the growth of plants, so there is a saving of the water that would be backwashed out of the pool, and so the assertion that it uses about the same amount of water.

Is a wetlandPOOL warmer or cooler than a normal more conventional pool?

A wetland pools is warmer than a conventional pool if neither are heated. This is because the wetland pool has a larger surface area to volume ratio as the wetland is usually shallow. A wetland pool is also generally darker than a conventional pool and this adds to the higher temperature.

There is no reason why a wetland pool can't be heated, but as the water tempreature increases, so the water can hold less and less oxygen to aerate the filter. Thus above 28 degrees the pool will begin to suffer unless there is extra added aeration. If you want to heat a pool, we obviously recommend a solar heater as this uses less power, and a small seperate pump is used to push water through the solar heater during the warmer hours of sunshine.

Does a wetlandPOOL use less energy?

A wetlandPOOL uses less energy than a conventional pool. This is because we usually use more efficient submersible pumps than conventional swimming pool pumps, and because the water flow requirement is very different for a wetland pool.

A conventional pool pump needs to run an pool cleaner and force the water through a restricted, contained sand filter. Both of these require a lot of water pressure, and so the pumps have what is referred to as a higher head height. This is not neccessary with a wetland pool, and so the pumps we use can be more efficient at moving water in larger volumes, rather than pushing water at a high pressures. Conventional pool pumps are also usually set outside the pool, and so extra energy is needed to move the water along pipes to the pump, and then back to the pool. Because of this, conventional pool pumps are usually designed with impellers that can suck air as they are often mounted above the water level, and so need to suck up air in order to prime themselves. Impellers that can suck air and water are less efficient than ones designed only for pumping water. External pool pumps are also usually noisy and unsightly, so we try to avoid them.

For a wetland pool, we usually use small, efficient, submersible pumps. If we need more water flow, then we use two or three smaller pumps, each with their own piping system to minimise the energy loss through pipe friction. The pump sizes vary from 63 Watts to 285 Watts. We generally don't use larger pumps. Using more than one pump also has the advantage that as the pump requirement drops, so you can switch of one or more pump to use less power. The pump requirement drops when the water tempreature drops in winter, and after as the filter matures, so the flow requirement drops.

With a pool larger than a hundred square meters, the pump size requirement for a wetland pool begins to taper off. Because the wetland is an ecosystem, the larger the ecosystem, the more stable it is. Thus larger pools don't need larger pumps, but have smaller more specific pumps doing specific tasks.

Examples of the use of energy in wetland pools are as follows:

Example 1 - A small pool (5 m x 2 m with an average depth of 1.5 m) with a swimming area of 15 000 liters and a wetland of 10 000 liters, with a 0.155 kW pump uses a total of 111.6 kWh of electricity monthly, which in Johannesburg would cost approximately R 66.96 monthly. (as of July 2010)
Example 2 - A large pool (15 m x 2.5 m with a depth of 1.7 meters) with a swimming area of 74 000 liters and a wetland of 37 000 liters has 3 pumps of 0.155 kW uses a total of 334.8 kWh monthly, which in Johannesburg would cost approximately R 200.80 monthly. (as of July 2010)

What about chemicals?

Whereas a conventional swimming pool uses chlorine or a salt water chlorinator, a wetlandPOOL uses no chemicals. Conventional pools use chlorine, acids, salts, algaecide and any other of a variety of chemical packs, with secret ingredients guaranteed to poison algae, bugs and all other life. Of course, nearly all of these are poisonous to a small degree to humans, as we are organic life forms too!

There are a number of chemical tricks available for fresh water ponds or koi ponds such as barley extracts, water softeners or pH stabilizers. We have found that these are on the whole unnecessary. We don't suggest that a wetlandPOOL have a specific pH, Oxygen content, water hardness or temperature. We have found that in different regions and with different plants, these can vary dramatically. A well functioning eco-system tends to balance things out.

What about sunscreens?

There is an argument that sunscreens will poison your pool if a large quantity of it enters your pool system. We have not had this problem yet with any of our pools, but are wary that their may be an issue, so we caution restraint, but do not suggest that people not wear sunscreen.

There are rock oil sunscreens available at great cost, and these are meant to be less poisonous to natural systems. The manufacturers of such sunscreens are not testing their products on animals, and so I cannot conclusively tell you whether they are harmfull to the eco system.