Aquatic Technology Pool & Spa
Paolo Benedetti
Infinity edge pool, vanishing edge pool, knife edge pool, perimeter overflow pool, wet edge, zero edge, flooded deck pool, slot overflow pool, elevated perimeter overflow pool, disappearing edge pool... what ever you call them, they all have something in common - water flows over the top of at least one wall of the pool.
Imagine a bowl of water overflowing it's rim, or if the top is not exactly level - the water overflows in the lower area. This brings us to the various types of edge details available.
The "hottest" detail and most difficult to construct is a perimeter overflow detail called a "knife edge." The knife edge perimeter overflow pool has the water raised right up to the level of the coping. But instead of any water flowing over the coping, the water drops into a diagonal slot that meets the top inside edge of the coping. The water is right at the top edge of the coping, but then it falls into the slot that is under the coping. This is the most complex design, due to the difficulty in constructing the gutter & "knife edge." The edge must be dead-on level. Additionally, because the coping covers the entire gutter, there is no opportunity to go back & rework or waterproof the gutter, without breaking out coping stones.
The second most popular edge detail, goes by many names: "wet deck," "flooded deck," & "slot overflow." As it's name implies, the water flows over the top of a portion of the coping stones, before dropping into a gutter or slot. Amateurish designers & builders rely on garish plastic or metal grating atop an open gutter. This is a very industrial and archaic method of building this style of pool. These plastic grate gutter systems are still very popular in Europe & some developing countries, due to their ease of installation.
A more refined appearance for a perimeter overflow pool, can be achieved by overlapping the coping & decking stones over the gutter, leaving no more than a 1/2" gap - thus the "slot overflow" name. A gap wider than 1/2" is in violation of the ADA. It just asking for a toe/high heel to get stuck or torn off. This method also requires that the portion of stone that is to be underwater be durable, submersible, and installed absolutely level.
One of the most striking designs is one of my personal favorites, the elevated perimeter overflow pool. As the name implies, the walls of the pool are elevated above the grade & the water flows over the top of the wall. The raised portion can vary from a few inches in height to as high as 18". Any higher than 18" and the pool becomes difficult to enter. It also poses a safety issue for those standing on top of the wall, if it is any higher than 18".
Though I will never publish it, my personal pool is of this elevated overflow style. The face of the 18" elevated walls are clad with polished absolute black granite. The top surface (that spans the thickness of the wall), was treated to provide slip resistance. The surface of the granite was "flamed," resulting in a natural sanded type of texture. The interior is lined with a custom blend of black, gray, and deep purple mosaic glass tiles from Bisazza Mosaico, Vicenza, Italy.
The most familiar and common edge detail is the "vanishing edge," "infinity edge," or "disappearing edge" pool. These pools usually have one side of the pool lowered to meet the operating elevation of the water. The water spills over this wall(s) and into either a catch basin, or a gutter. Where a gutter is used, the water is transported to a remote holding tank, from where the edge effects pump draws it's water.
Adding to the complexity of all of these choices, is the myriad of combinations of the various effects. The most complex pool that my firm has ever designed & constructed (though not the most expensive), combined a staggered vanishing edge, knife edge, perimeter overflow, and collection gutters. Executed flawlessly, the final results are absolutely breathtaking. To review an in depth article about this project, visit the following link:
http://www.aquatictechnology.com/articles/t_cubed.htm
Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
©www.aquatictechnology.com
Aquatic Technology Pool & Spa, "Creating Water as Art."™
Pools as an art form - the way it should be!
Thursday, May 14, 2009
Saturday, May 9, 2009
Salt Water Pools - Chemical Free, Hardly!
Salt Chlorine Generator, Salt Water Pool, Salt Free Pool, wet edge, zero edge, Chemical Free Pool - whatever lie they perpetrate, the consumers are being scammed!
A few years ago, I stopped installing salt water pools and salt chlorine generators. Salt water in the pools were the direct cause of damage to the masonry and equipment. The lost credibility issue, the financial exposure for the warranty repairs, & call-backs from these negative effects were the primary reasons. Additionally, the manufacturer's of these salt chlorine units & the swimming pool industry in general, have misrepresented the facts about these vessels & salt-chlorine generation. The manufacturer's do not even provide disclaimers that these issues exist.
News flash - there is chlorine in your pool! First and foremost, these pool have salt in them for only ONE PURPOSE - that is to generate chlorine! A salt water pool is not a "chlorine free pool," as the swimming pool industry and the manufacturer's promote them. It is just that no one is required to pour it in the pool, from external sources. The only person who benefits is your pool service technician. They save money because they do not have to supply chlorine any longer. Now he can sell you salt instead - and it has to be a special type of finely ground salt, as regular water softener salt will not work (it contains anti-caking agents)!
Salt-chlorine generators CREATE CHLORINE, when the salt water passed through some electrolytic plates (cathode & anode) which separate the salt (sodium chloride) into sodium & chlorine... so see there is chlorine in the pool (you just do not see anyone pouring it in).
Though some people say that the water has a "silkier feel," I argue that this is subjective. A properly sanitized pool also feels smooth.
There are just too many negatives to using salt in a swimming pool. Even at low levels, salt dissolves masonry. Simple analogy: ever see the sidewalks in the Northeast where they throw salt on the cement to dissolve the winter ice? The concrete is rough & the aggregate is exposed - eaten away by the ravages of the salt. In a swimming pool the same is occurring to the plaster, concrete, stonework & grout.
I know of a pool builder on the SF Peninsula who had to replace an entire pool deck that was set using Durango stone. It seems that the soft marble from Mexico is not very resistant to the aggressive effects of the salt. It literally ate the deck in a period of months!
Another issue is the electroplating of metallic components within the pool. By placing salt into a pool, you are in effect creating a weak battery. The water is now the electrolyte, similar to that in a car battery. Due to the very nature of a pool, electrical energy from the grounding system of the property flows to the pool's structural steel. This causes the steel & all of the metal components to become energized by a weak electrical current (an electrode).
Guess what? If there is the slightest trace of metals in the water, you are in for some interesting phenomenons. And what water does not have SOME traces of metals in it (iron, copper, manganese, etc)?
The metals in the water become electrically attracted to the metal components... it is called electroplating. The metal parts start turning weird colors, iron starts collecting on the SS light rings, and the steel pattern becomes highlighted on the surface of the plaster.
If the pool does not have a sufficient quantity of metals naturally occurring in the water to supply the demands of this phenomenon, physics will begin to dissolve the softest metals present in contact with the water. This can be copper pipes (if it is a pre-circa 1960's pool), the copper heat exchanger in the heater, the copper solar panels, motor shaft seals, temperature sensors, anything metal in contact with the water.
If there is a copper heat exchanger in the pool heater, the softer metal (copper) will sacrifice itself in an effort to maintain the proper balance in the water. The heater literally gets eaten alive from the inside! This has absolutely nothing to do with poor water chemistry! It is all merely due to the presence of salt, water & electricity. Ocean moored boat owners have experienced this very phenomenon for decades. Brass & SS props literally dissolve in the ocean, as the small currents from their electrical systems mildly energize their props.
Some swimming pool contractors think that if they provide a sacrificial anode, like in the typical tank water heater or connected to a boat, they have solved the problem. Wrong! They have merely provided a softer metal to sacrifice itself first. Usually made of magnesium or zinc, these metals will cause dark gray, black or blue deposits on the pool walls or other metal components.
Another myth is that there is no need to add ANY chemicals to the pool. But, this could not be further from the truth! The chlorine generated by the equipment is referred to as "unstabilized chlorine." This means that it is easily degraded by the UV from the sun. Surprise... MOST POOLS ARE OUTDOORS!!! Without the addition of a UV stabilizer (AKA: cyanuric acid), what the salt chlorine generator makes is gone very quickly. SEE, there is just another chemical that they forgot to tell you about! It's not that cyanuric acid is bad... in fact it is a component in most powdered forms of chlorine, it is just that they tout their salt water pools as a "healthy chemical free pool."
Additionally, the production of chlorine from salt through the electrolytic process produces chlorine with a pH of around 13! There is a slight amount of sodium hydroxide (lye) created in the process, with a pH of around 2. But, there is not a sufficient quantity to buffer the high pH of the chlorine. Any pool service company will tell you that these pools frequently have high pH's each week. In order to control the high pH they must add significant quantities of muriatic acid (sometimes a whole gallon each week!).
The biggest drawback of these systems, is that they generate the chlorine at an even & consistent rate. They do not vary their output based upon the demands in the pool. The fact that these systems do not monitor or test the water chemistry, results in spikes & drops in the dosage of chlorine. Set too low you have too little chlorine & you get algae & biological contaminants. Have a birthday party with 30 kids & forgot to turn it up, and the pool turns brown & people get sick. Turned it up after the birthday party to eliminate the brown water, but forgot to turn it back down? Guess what? - you just bleached your wife's new Prada bikini when she uses the spa!
Sodium chloride, sodium hydroxide, sodium hypochlorite, muriatic acid, cyanuric acid...
and you thought that you were swimming in a chemical free & hassle free pool!? With all of that stuff in there, it should feel thick & chunky!
The solution.... save the money you would have spent on the salt chlorine generator & install an ORP/pH controller ($2,500 + (2) peristaltic pumps @ $350 each). These systems monitor the water while the pumps are running. They sense changes in the water chemistry, and micro-dose the water with liquid chlorine and a diluted solution of muriatic acid (for pH control). Hot 100ºF day with 30 kids over? The controller senses the drop below the settings & starts dosing the chemicals to maintain a balanced pool. Experience an unusually cool overcast period? Not to worry, the controller does not feed when there is no demand.
An alternative to storing the muriatic acid solution, is to install a CO2 system. A cylinder of CO2 gas (similar to a welding cylinder) is secured to a wall or wooden post. An electronic solenoid valve attached to the cylinder, opens as needed to inject CO2 into the plumbing at the equipment pad. The CO2 turns into carbonic acid, thereby buffering the pH. This is a simple solution which is inexpensive safe method - except for the periodic requirement of exchanging cylinders. If you do not chose to drive to the local gas supplier or carbonic beverage distributor, there are some commercial gas cylinder exchange services which will provide cylinders on an exchange basis.
Used in conjunction with an ozone generator, these settings can be set at a minimum level. The ozone takes over the responsibilities of oxidizing the bather waste, leaving the chlorine to sanitize the pool. This is called a "synergistic relationship," as they exist for each other's benefit, providing an exponentially larger contribution to safe & clear water, than if used alone.
The water is maintained crystal clear, free of contaminates that burn the eyes. FYI: it is bather waste (sweat, urine, make-up, deodorants, sunscreens, etc.) combined with chlorine, that creates ammonia compounds that burn the eyes! It is not "too much chlorine" as everyone has been led to believe for years! The smell of chlorine on your skin when you get out of the pool, is actually these very ammonia compounds that have formed on your skin from your perspiration & sunscreens! Again, it is not from there being too much chlorine in the pool!
Commercial pools are required to maintain a minimum of 2 ppm of chlorine. I have personally swam in pools with levels as high as 6 ppm. While it will bleach swim suits faster (not noticeable in one swim), it is totally safe!
It is the LACK of chlorine and improperly balanced pH that causes burning eyes and the smell of chlorine around the pool (off gassing of these ammonia compounds). This is why the problem is so prevalent at low end commercial pools (motels, hotels, apartment & condo complexes). They usually have just a chlorine feed pump that is set at one feed rate - one that is easily overwhelmed on a hot day with 500 people - just like a salt chlorine generator would be!
Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
©www.aquatictechnology.com
A few years ago, I stopped installing salt water pools and salt chlorine generators. Salt water in the pools were the direct cause of damage to the masonry and equipment. The lost credibility issue, the financial exposure for the warranty repairs, & call-backs from these negative effects were the primary reasons. Additionally, the manufacturer's of these salt chlorine units & the swimming pool industry in general, have misrepresented the facts about these vessels & salt-chlorine generation. The manufacturer's do not even provide disclaimers that these issues exist.
News flash - there is chlorine in your pool! First and foremost, these pool have salt in them for only ONE PURPOSE - that is to generate chlorine! A salt water pool is not a "chlorine free pool," as the swimming pool industry and the manufacturer's promote them. It is just that no one is required to pour it in the pool, from external sources. The only person who benefits is your pool service technician. They save money because they do not have to supply chlorine any longer. Now he can sell you salt instead - and it has to be a special type of finely ground salt, as regular water softener salt will not work (it contains anti-caking agents)!
Salt-chlorine generators CREATE CHLORINE, when the salt water passed through some electrolytic plates (cathode & anode) which separate the salt (sodium chloride) into sodium & chlorine... so see there is chlorine in the pool (you just do not see anyone pouring it in).
Though some people say that the water has a "silkier feel," I argue that this is subjective. A properly sanitized pool also feels smooth.
There are just too many negatives to using salt in a swimming pool. Even at low levels, salt dissolves masonry. Simple analogy: ever see the sidewalks in the Northeast where they throw salt on the cement to dissolve the winter ice? The concrete is rough & the aggregate is exposed - eaten away by the ravages of the salt. In a swimming pool the same is occurring to the plaster, concrete, stonework & grout.
I know of a pool builder on the SF Peninsula who had to replace an entire pool deck that was set using Durango stone. It seems that the soft marble from Mexico is not very resistant to the aggressive effects of the salt. It literally ate the deck in a period of months!
Another issue is the electroplating of metallic components within the pool. By placing salt into a pool, you are in effect creating a weak battery. The water is now the electrolyte, similar to that in a car battery. Due to the very nature of a pool, electrical energy from the grounding system of the property flows to the pool's structural steel. This causes the steel & all of the metal components to become energized by a weak electrical current (an electrode).
Guess what? If there is the slightest trace of metals in the water, you are in for some interesting phenomenons. And what water does not have SOME traces of metals in it (iron, copper, manganese, etc)?
The metals in the water become electrically attracted to the metal components... it is called electroplating. The metal parts start turning weird colors, iron starts collecting on the SS light rings, and the steel pattern becomes highlighted on the surface of the plaster.
If the pool does not have a sufficient quantity of metals naturally occurring in the water to supply the demands of this phenomenon, physics will begin to dissolve the softest metals present in contact with the water. This can be copper pipes (if it is a pre-circa 1960's pool), the copper heat exchanger in the heater, the copper solar panels, motor shaft seals, temperature sensors, anything metal in contact with the water.
If there is a copper heat exchanger in the pool heater, the softer metal (copper) will sacrifice itself in an effort to maintain the proper balance in the water. The heater literally gets eaten alive from the inside! This has absolutely nothing to do with poor water chemistry! It is all merely due to the presence of salt, water & electricity. Ocean moored boat owners have experienced this very phenomenon for decades. Brass & SS props literally dissolve in the ocean, as the small currents from their electrical systems mildly energize their props.
Some swimming pool contractors think that if they provide a sacrificial anode, like in the typical tank water heater or connected to a boat, they have solved the problem. Wrong! They have merely provided a softer metal to sacrifice itself first. Usually made of magnesium or zinc, these metals will cause dark gray, black or blue deposits on the pool walls or other metal components.
Another myth is that there is no need to add ANY chemicals to the pool. But, this could not be further from the truth! The chlorine generated by the equipment is referred to as "unstabilized chlorine." This means that it is easily degraded by the UV from the sun. Surprise... MOST POOLS ARE OUTDOORS!!! Without the addition of a UV stabilizer (AKA: cyanuric acid), what the salt chlorine generator makes is gone very quickly. SEE, there is just another chemical that they forgot to tell you about! It's not that cyanuric acid is bad... in fact it is a component in most powdered forms of chlorine, it is just that they tout their salt water pools as a "healthy chemical free pool."
Additionally, the production of chlorine from salt through the electrolytic process produces chlorine with a pH of around 13! There is a slight amount of sodium hydroxide (lye) created in the process, with a pH of around 2. But, there is not a sufficient quantity to buffer the high pH of the chlorine. Any pool service company will tell you that these pools frequently have high pH's each week. In order to control the high pH they must add significant quantities of muriatic acid (sometimes a whole gallon each week!).
The biggest drawback of these systems, is that they generate the chlorine at an even & consistent rate. They do not vary their output based upon the demands in the pool. The fact that these systems do not monitor or test the water chemistry, results in spikes & drops in the dosage of chlorine. Set too low you have too little chlorine & you get algae & biological contaminants. Have a birthday party with 30 kids & forgot to turn it up, and the pool turns brown & people get sick. Turned it up after the birthday party to eliminate the brown water, but forgot to turn it back down? Guess what? - you just bleached your wife's new Prada bikini when she uses the spa!
Sodium chloride, sodium hydroxide, sodium hypochlorite, muriatic acid, cyanuric acid...
and you thought that you were swimming in a chemical free & hassle free pool!? With all of that stuff in there, it should feel thick & chunky!
The solution.... save the money you would have spent on the salt chlorine generator & install an ORP/pH controller ($2,500 + (2) peristaltic pumps @ $350 each). These systems monitor the water while the pumps are running. They sense changes in the water chemistry, and micro-dose the water with liquid chlorine and a diluted solution of muriatic acid (for pH control). Hot 100ºF day with 30 kids over? The controller senses the drop below the settings & starts dosing the chemicals to maintain a balanced pool. Experience an unusually cool overcast period? Not to worry, the controller does not feed when there is no demand.
An alternative to storing the muriatic acid solution, is to install a CO2 system. A cylinder of CO2 gas (similar to a welding cylinder) is secured to a wall or wooden post. An electronic solenoid valve attached to the cylinder, opens as needed to inject CO2 into the plumbing at the equipment pad. The CO2 turns into carbonic acid, thereby buffering the pH. This is a simple solution which is inexpensive safe method - except for the periodic requirement of exchanging cylinders. If you do not chose to drive to the local gas supplier or carbonic beverage distributor, there are some commercial gas cylinder exchange services which will provide cylinders on an exchange basis.
Used in conjunction with an ozone generator, these settings can be set at a minimum level. The ozone takes over the responsibilities of oxidizing the bather waste, leaving the chlorine to sanitize the pool. This is called a "synergistic relationship," as they exist for each other's benefit, providing an exponentially larger contribution to safe & clear water, than if used alone.
The water is maintained crystal clear, free of contaminates that burn the eyes. FYI: it is bather waste (sweat, urine, make-up, deodorants, sunscreens, etc.) combined with chlorine, that creates ammonia compounds that burn the eyes! It is not "too much chlorine" as everyone has been led to believe for years! The smell of chlorine on your skin when you get out of the pool, is actually these very ammonia compounds that have formed on your skin from your perspiration & sunscreens! Again, it is not from there being too much chlorine in the pool!
Commercial pools are required to maintain a minimum of 2 ppm of chlorine. I have personally swam in pools with levels as high as 6 ppm. While it will bleach swim suits faster (not noticeable in one swim), it is totally safe!
It is the LACK of chlorine and improperly balanced pH that causes burning eyes and the smell of chlorine around the pool (off gassing of these ammonia compounds). This is why the problem is so prevalent at low end commercial pools (motels, hotels, apartment & condo complexes). They usually have just a chlorine feed pump that is set at one feed rate - one that is easily overwhelmed on a hot day with 500 people - just like a salt chlorine generator would be!
Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
©www.aquatictechnology.com
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