Maintenance for Natural Swimming Pools

One way to appreciate the advantages of natural swimming pools over conventional pools is to compare the amount and type of pool maintenance each type of pool requires. Unlike a traditional swimming pool, a natural swimming pool contains no sanitizing chemicals and never smells like chlorine (which occurs, by the way, when a chlorinated pool has a chlorine deficiency, not an excess). That's because the water in a natural pool is purified by a biological filter provided by plant life.

Natural swimming pools aren't just for swimming. They are landscape water features akin to water gardens, and you have to maintain them as such. Just as it does for a traditional pool, maintenance involves removing debris, cleaning filters and monitoring overall water quality, including pH, but you never have to check chlorine or salt levels and add more. Instead, you have to tend your garden.

Natural swimming pools are drawing the interest of an increasing number of ecologically and DIY-minded homeowners, and the companies that install them point to the lower maintenance requirements as a selling point. No one ever claims that they require no maintenance, however. Even though the pool looks exactly like a natural pond that is perfectly capable of taking care of itself — and to some extent, it is — it still needs pool maintenance to maintain its health, but that maintenance is minimal.

The water in a natural swimming pool has to circulate freely between the swimming area and the regeneration zone, where the plants live, and the pool design usually includes at least one skimmer or mesh filter — and usually more than one — to catch leaves and other large debris and keep them from bogging down the garden area. You have to clean these skimmers and filters regularly, or water won't be able to circulate, and that's a job that takes five minutes maximum. You might also have to use a skimmer on a long handle to remove leaves from the middle of the pool, which may add another five minutes to the job.

If you want the swimming experience to be pleasant, pool maintenance should also involve cleaning debris from the bottom of the swimming area. Depending on the pool lining material, you can use a handheld pool vacuum or a robotic one. You may also have to occasionally remove the slick coating of organic material that collects on the pool's underwater surfaces by manually scrubbing it, which is a safety measure since this coating makes the surfaces slippery and hazardous.

A well-designed water garden, which is the filtration system of a natural swimming pool, is largely self-regulating, but like any garden, it needs extra help to get established and occasional seasonal maintenance afterward. It's a good idea to introduce as many mature plants as possible at the beginning if you're in a hurry to use the pool, and you'll need to prune these and clear away dead growth to prevent them from crowding the younger plants. Once the garden is established, it becomes an ecosystem whose various parts respond to all the others, but it still needs a gardener's helping hand to thrive.

Over time, an anaerobic layer of silt settles on the bottom of the garden zone, and this should be cleaned to allow the plant roots to breathe. Without oxygen, they won't be healthy, and unhealthy plants can't absorb nutrients, which means they can't do the work of purifying the water. This job must be done every three to five years, and it's one you may want to pass on to a pool maintenance contractor.

One great thing about natural swimming pools is that you can leave them uncovered and basically "as is" throughout the winter and let the water freeze over, but if you choose plants that aren't winter hardy, you'll have to replace them in the spring. You'll also need to keep a garden hose handy throughout the summer to maintain the water level, which goes down faster than it does in a regular pool owing to evaporation through the plant foliage.

If the filtration system established by the aquatic plants is functioning properly, you shouldn't notice too much algae growth in the pool because the plants use up all the nutrients. Algae can quickly become a problem, however, if the circulation pumps are blocked, if a significant portion of the pool is in direct sunlight or if soaps containing phosphates — a prime nutrient for algae — are introduced into the water. You may also have an algae problem if the pool is too small because the algae don't have room to circulate and tend to clump together. When algae growth becomes noticeable, you have to do something before the algae outcompete the plants in the regeneration zone for nutrients and take over.

One recommended way to control algae in the swimming area is to introduce pond dye into the water. This safe-to-use dye is highly concentrated, and it turns the water just dark enough to discourage algae growth without staining hair or skin. A half teaspoon treats 50,000 gallons of water, and it is best used in early spring or when the pool is new and the garden isn't yet established. Just sprinkle it on the surface of the water and let it circulate throughout the system.

If you've ever had a chlorinated pool, you know that it needs daily maintenance. You have to check the chlorine levels and add more when necessary, and you also have to keep an eye on the pH level of the water and adjust it when it becomes too high or too low. If you don't do this, the chlorine doesn't sanitize properly, and the pool water turns cloudy and unhealthy. Algae growth is also a problem in conventional pools and is usually controlled with special chemicals or by shocking the pool with a large amount of chlorine.

Saltwater pools aren't much easier to maintain. Even though you introduce salt rather than chlorine, it basically becomes chlorine when it dissolves, so the pool is subject to the same problems that beset a chlorine pool and takes the same amount of maintenance. In fact, a saltwater pool requires a little more maintenance because you have to keep your eye on the chlorine generator and occasionally service it. Moreover, saltwater is corrosive, so you need more durable pool hardware than you do for a chlorinated pool, and even then, it may deteriorate and need replacement.

You do have to monitor the pH level of a natural pool. The ideal pH in a conventional swimming pool is slightly alkaline, with a value between 7.2 and 7.6, and the same is true for natural swimming pools, although the water will probably tend to be slightly acidic because of the plant life it supports. The plants will suffer if the pH falls below 6.0, however; it will be harder to control algae, and the water will strip natural oils from your skin. It's easy to raise the pH by adding baking soda, a naturally alkaline chemical that won't otherwise upset the chemical balance of the water, but you probably won't have to do this.