Automated pool cleaner

Type of vacuum cleaner for swimming pools

An automated pool cleaner is a vacuum cleaner that is designed to collect debris and sediment from swimming pools with minimal human intervention.

Swimming pool cleaners evolved from the water filter and early cistern cleaners. The forerunner of today's pool cleaners were cistern cleaners; they were developed due to the need to clean pools and cisterns. Thermae were well known for their elaborate cisterns and prevalent in the early United States. The United States Patent and Trademark Office refers to a cistern cleaner patent filed (though never issued) as early as 1798. In 1883 John E. Pattison of New Orleans applied for a "Cistern and Tank Cleaner" and the first discovered patent was issued the following year. It swept and scraped the bottom of a cistern or tank and, through a combination of suction and manipulation of the water pressure, was able to separate and remove sediment without removing the water. Over the next 20 years his invention was revised multiple times. Many pool cleaner patents issued in the modern era refer to some of the cistern cleaners as predecessors of their invention.

The first swimming pool cleaner was invented in 1912 by Pittsburgh, Pennsylvania citizen John M. Davison. On November 26, 1912, he submitted a patent application to the United States Patent and Trademark Office entitled "Cleaning Apparatus For Swimming Pools And The Like", which was issued on March 25, 1913. The first suction side pool cleaner was invented by Roy B. Everson of Chicago in 1937 and was named the "Swimming Pool Cleaner". In 1953, another notable suction side pool cleaner was created by Joseph Eistrup, who called his invention "Pool Cleaner". Two years later, the "Automatic Swimming Pool Cleaner" was created by Andrew L. Pansini; it was the first truly automatic pool cleaner and was touted by Pansini as "effective to remove the scum, dirt and other accumulations from both the bottom and sidewalls of a pool to disperse foreign matter in the water for removal therefrom by a normal pump filter system of the pool". The first robotic pool cleaner that used electricity was invented by Robert B. Myers in 1967. The pressure side cleaner was invented by Melvyn Lane Henkin in 1972. It was called the "Automatic Swimming Pool Cleaner" and it used three wheels to allow the machine "to travel underwater along a random path on the pool vessel surface for dislodging debris therefrom". The design is used in the Polaris Pool Cleaner, a commonly used pool cleaner amongst modern pool owners. Independently from his American counterparts, Ferdinand Chauvier, a hydraulics engineer who emigrated to South Africa from the Belgian Congo, introduced the Kreepy Krauly in Springs, South Africa, in 1974.

There are three main types of automated or automatic swimming pool cleaners, classified by the drive mechanism and source of power used: a suction side cleaner, a pressure side cleaner, and an electric robotic cleaner.

This type of pool cleaner pumps water out of the pool via its skimmer or drains, uses it for locomotion and debris suction, then returns it after being filtered via pool return or outlet valves. This is the least expensive and most popular type of cleaner, and it traces a random course around the pool. This type of cleaner is usually attached via a 1.5 inch hose to a vacuum plate in the skimmer, or a dedicated extraction or "vac" line on the side of the pool. The suction action of the pool's pump provides the needed force for the machine to randomly traverse the floor and walls of the pool, extracting dirt and debris in its path. The first automatic pool cleaner was a suction cleaner. Suction side cleaners are the least expensive and most widely used pool cleaners. The price of suction side cleaners ranges from $250 $650. They are powered solely by the main pump of the pool and utilize the pool's filter system to remove dirt and debris from the water. Suction side cleaners are best suited for screened in pools or those with light debris such as sand. Large amounts of debris or larger debris such as leaves and sticks can easily clog the unit or its pump basket. These machines effectively diminish the suction of the main pump using them will increase the electricity costs and require the main pump and filter system to be serviced more frequently. There are minimal maintenance and part replacement costs on these devices over time.

In this design, pool water inflow is further pressurized using a secondary "booster" pump on most but not all models. This high pressure water is used for locomotion and debris suction to exploit the Venturi effect. The cleaner traces a random course around the pool. The requirement of a booster pump makes pressure side cleaners the most expensive in terms of electricity use. The pressure causes turbulence in the water, distributing some debris onto the floor and walls of the pool, some of which are re floated to the pool surface before being sucked into the main filter through the skimmer inlets. A portion of the dirt and debris is caught in an attached filter bag. Pressure side cleaners are better suited for handling a heavy amount of debris. They are also better for large debris such as leaves, acorns, and sticks. The purchase cost of this type of cleaner range from $200 to about $700 plus the costs of the booster pump, usually over $200. Some more sophisticated models can cost over $1,000. Both suction side and pressure side cleaners are dependent on the pool's main pump and filter system to remove contaminants from the pool water, which results in the inability to remove particles smaller than the pore size of the pool's existing filter element. Such elements can be sand, diatomaceous earth, zeolite, or other natural or synthetic materials. That particle size ranges from under 5 μm for diatomaceous filters to 50+ μm for sand filters.

These cleaners are independent of the pool's main filter and pump system and are powered by a separate electricity source, usually in the form of a set down transformer that is kept at least 10 feet (3 m) from the pool. They have two internal motors: one to suck in water through a self contained filter bag and eject the filtered water back into the pool, and another that is a drive motor connected to tractor like rubber or synthetic tracks and "brushes" tied by rubber or plastic bands to a metal shaft. The brushes, which resemble paint rollers, are located on the front and back of the machine and help remove contaminant particles from the pool's floor and walls (in some designs even the pool steps are included) depending on size and configuration. They also direct the particles into the internal filter bag. An internal microchip is programmed to control the drive motors. The chip causes the machine to change direction when it reaches a wall or the water surface after climbing the pool walls. These machines may also be directed by sensors located in the bump bars which, on contact with objects such as a wall, cause a reverse in direction, with a small offset allowing it to move one machine's width over on each crossing of the pool. The delay timer is an important feature for many pools, as many switch off several circulation pumps during the night to allow suspended particles to settle on the bottom of the pool; after a couple of hours, the pool cleaner begins its cleaning cycle. This cleaning cycle is set up to complete before the pumps are turned back on. Although the feature is not necessary for adequate pool cleaning, it saves energy and improves cleaning efficiency. To move forward and backward and navigate walls and steps, electric robotic cleaners rely on three natural principles: traction and movement caused by the drive motor and tracks, buoyancy created by the large areas inside the machine that fills with air, and the force resulting from the high pressure of water being emitted from the top of the machine that pushes it against the floor and walls. Some electric robotic machines use brushes made out of polyvinyl alcohol (PVA), which has an adhesive quality that allows the unit to cling to the walls, steps, and floors. It is resistant to dirt and oil, which improves its lifespan over rubber or other synthetic materials. The combination of these three natural principles and an internal mercury switch that tells the microchip that the unit has gone from a horizontal to a vertical position allows it to change direction from ascending to descending the wall at pre programmed intervals based on the average height of swimming pool walls. Some machines have delayed timers that cause the robot to remain at the waterline, where more dirt accumulates, to momentarily scrub. The major benefits of these machines are efficiency in time, energy, and cleaning ability and low maintenance requirements and costs. The major disadvantage is purchase cost which can range from $1,000 to $1,500. The smart navigation system on the product makes it possible to cover the entire area with ease.

All commercial pool cleaners are electric robotic and can range in price from a little over $1,000 to upwards of $15,000. They closely resemble residential models but in addition to their addition size, they are made with heavy duty components, more sophisticated computer guidance, and on and off systems. In the US, commercial pool cleaners need to be certified by the National Spa Pool Foundation (NSPF) as Certified Pool Operators (CPO).

There have been attempts for nearly 100 years to mandate the use of pool cleaners, primarily addressed to public pools. The Centers for Disease Control and Prevention in Atlanta, Georgia, on a grant provided by the National Swimming Pool Foundation (NSPF), published the first uniform Model Aquatic Health Code (MAHC).

In 2005 the CDC, in response to growing concern and feared epidemic with the pathogen Cryptosporidium, much like the APHA did in 1912, gathered many of the United States' foremost medical and scientific experts to study the concern for aquatic health. As a result, in 2007 they began to consolidate a uniform aquatic health code. Each health and safety segment was assigned to a committee to study it and draft a proposed module open for public comment before being adopted and recommended to the nation's 3200+ state and local health agencies that enact ordinances and regulations for swimming pools and spa and other aquatic facilities, inspect and monitor the facilities, and enforce the regulations. Since the focus of the MAHC was to respond to the threat of Cryptosporidium the Technical Committee of Recirculation Systems and Filtration is a major focus. University of North Carolina Charlotte Associate Professor James Amburgey conducted many tests to evaluate existing swimming pool filters and he concluded that they have been extremely ineffective in removing Cryptosporidium in most cases.