by Mark Garcia April 27, 2015
There's been a lot of conversation surrounding Natural pools, which are filtered naturally with a specially graded biofilter, kind of a natural septic field, and use aquatic plants that suck up the impurities.
A natural pool does not use chlorine, but you still need to maintain the water balance, and you still need to maintain the filters. You don't backwash a natural pool - but cleaning and tending to the biofilter and plants is necessary to keep a natural pool healthy.
If you've watched any recent episodes of the POOL MASTER, on the animal planet, or have seen pictures floating around the internet about "Natural" pools, you have an idea of what a natural pool is - let's take a deeper dive, shall we?
Absolutely! From a biological perspective, natural pools are quite sanitary. There are hundreds of public natural swimming pools, which operate within new standards created specifically for managing the health of a natural pool. The biofilter, or regeneration zone, traps and absorbs bacteria and germs, while aquatic plants suck up phosphates and other micro-contaminants, while releasing oxygen into the water. Water balance is decidedly different than in a traditional pool. pH levels in natural pools are run quite low, 6.5-7.0, which retards most algae and bacteria growth, and is preferred by the aquatic plants that are planted in the regeneration zone.
In some cases, there is no need to "winterize", as one would do with a traditional pool, since natural pools don't use traditional aboveground equipment. Where a submersible pump is used, a winterization process is simpler. With systems using aboveground equipment, or pipes near the surface, draining the equipment and blowing the pipes is recommended. Natural pools can be covered with a winter cover or mesh net to keep it clean. Plants in the regeneration zone can be cut-back and also net-covered if needed to keep out leaves and debris.
They can, but they must be kept in the swimming area, and not in the regeneration zone, and they cannot be fed any type of packaged food. Koi ponds require slight differences in water management, and most natural pools are designed to be a fish-free zone, and although fish can survive and thrive in a natural pool, it is not recommended as they consume vital microbes and add a considerable amount of contaminants to the water. Ducks and other water fowl are also discouraged, because they eat the plants and do their business in the water.
The regeneration zone as it's called, is an area as large as the pool itself, or as large as the swimming area. Water is pumped from the swimming area, to the top of a natural pool filter that spreads out over hundreds of square feet and is 3-5 feet deep, graded with a mix of gravel, sand and natural minerals to filter and purify the water, just as it's done in nature.
Due to the natural lagoon like effect, a natural pool may attract certain amphibians like frogs or woodland creatures, water fowl or turtles. Most snakes do not like water, however they may be found near the edges of a regeneration zone. Mosquitos (skeeters), won't lay eggs in a natural pool because it is water in motion, and not a stagnant pond. One of the best things about a natural pool, according to its' proponents, is the harmony and co-existence with nature.
Yes, there are no disinfectants or sanitizers used in a natural pool. Ozone, UV and mineral purifiers are also not used in a truly natural pool. No algaecides, no clarifiers and certainly no chlorine, all of which will destroy the natural equilibrium of the system. Natural pools do still need effective levels of pH, alkalinity and calcium hardness, and may need additions of these water balance chemicals. Pool enzymes can be used, I think - without losing the "natural pool" designation.
They cost more than a normal pool, in most cases. This is primarily due to the space required for the regeneration zone, and the depth of the swimming area, recommended to be 4-6 feet. The average price for a residential-sized natural pool would be $50-$75K, and that's if you have a builder near you that offers natural pools. If you have to hire an out of town contractor, this will increase the price.
A natural pool will require more space than a traditional pool, because for best results the regeneration area should be almost as large as the swimming area.
However, if space is a consideration, the natural filter ore regeneration zone can be deeper and more compact, as shown in this image on the right by avalonlandscapes.co.uk, which has melded traditional and natural pool designs quite nicely.
Natural pools can be built in nearly all climate zones, and in snowbelt regions of the US, natural pools will freeze just as any pool will, solid across the surface during winter months. Some aquatic plants that don't survive winter will need to be replaced each spring. In Minnesota, a natural pool of over 21,000 sq. ft. is currently being constructed, and in the winter, they plan to use the natural pool as an outdoor ice skating rink.
Evaporation is accelerated in a natural pool due to the respiration of the plants. Rainy periods may provide enough to compensate, but during hot and dry months, the natural pool will need to have water added from your garden hose to maintain the water level. Normal tap water is fine, although a garden hose water filter is recommended to remove chlorine, metals and bacteria.
It takes a few seasons for the natural equilibrium to take hold, which improves natural filtering and cleanliness of the water. Brushing and netting of the natural pool is an ongoing bit of maintenance, to keep surfaces of the swimming area clean, and to remove debris from the regeneration zone. Put on your muck boots, cleaning a natural pool filter is much like weeding a garden, only you are standing in 6 inches of water. Every month or two, the plants should be trimmed of any dead leaves, and the floor around the plants cleaned of any sticks or leaves.
Just like any other pool, a natural pool will require a safety fence that conforms to local standards. The electrical equipment, such as the pump and lighting, should be installed in accordance with NEC 680 and any local codes governing bonding. Since most natural pools are too shallow for safe diving, diving boards or dive rocks are discouraged without proper engineering. Pool alarms can be used for natural pools, but may not be as effective as secondary fencing or other access restrictions.
Thanks for Reading!