Hair Entanglement in Pools, Are Current Standards Adequate?
When discussing hair entanglement in the pool and how to prevent these types of incidents from occurring, we have to look at a few things. The first is line velocity. If it is low enough, hair won’t be ingested by the pipe and tangled under the drain lid. Suction entrapment wouldn’t occur either, even if a grate were missing.
The second issue pertains to the current codes and standards. Some states have state building codes that dictate maximum line velocities for energy efficiency. California and Florida both mandate line velocities of 6 FPS suction and 8 FPS returns for energy efficiency.
Residential In-ground Pools NSPI-5/2003 (9.2) the line velocities were limited to 8 FPS suction and 10 FPS returns. (9.2.1) the limit through the drain cover was limited to 1.5 FPS.
Residential In-ground Pools NSPI-5/2013 (9.2) the line velocities were limited to 8 FPS suction and 8 FPS returns. (9.2.1) the limit through the drain cover was deferred to the APSP-7 standard.
Suction Entrapment Avoidance APSP-7 (2013) Piping line velocity is not specified, though the flow rate through the drain cover is limited to 1.5 FPS.
APSP-15 Energy Efficiency Code (2011) 6 FPS suction and 8 FPS return
ISPSC 2015 (311.3) limits the line velocities in the return piping to 8 FPS. (310) It defers to the specifications in APSP-7 (there is no longer a suction line velocity in the standard).
Suction Outlet Fitting Assemblies APSP-16/2017 (3.9.2) piping line velocities were eliminated, though 1.5 FPS remained as the line velocity through the RDP/SOFA.
The safety standards are not addressing energy efficiency. Most experts agree that the optimum efficiencies are achieved at 6 FPS suction and 8 FPS return line velocities. The majority of hydraulic engineers are designing at 4.5 FPS suction and 6 FPS return line velocities. This allows for a margin of error and minor deviations that may occur during construction, while still staying below the maximums. Most codes for public pools recognize the need for low line velocities and therefore limit the velocities at the pipe connected to the main drain to 1.5 – 3 FPS.
The safety standards assume two things occur. The first assumption is that the drain sump size is compliant with the SOFA requirements and the manufacturer’s specifications. Field-built sumps (divots carved out of the shotcrete) are oftentimes too shallow. Few builders thicken the shotcrete around the suction pipes to allow for a proper depth sump.
The decreased distance between the suction pipe and the underside of the drain cover increases the flow through the drain cover. This increases the danger of hair entanglement, as the design standards and flow rate through the cover have been exceeded. Therefore the sumps are of insufficient size and volume to slow the velocity of the water.
Swimming Pool Expert Witness
Photo Credit: Getty Images
What Were The Builders Thinking With This Movable Pool Floor?
A pool builder experimenting with movable pool floors was a costly lesson. Learn how this moving pool floor project was saved.
It started with a phone call from the owner’s personal assistant. They had movable pool floors in the pool and spa that didn’t operate properly. They wondered if I’d fly up to Whitefish, MT, and have a look-see at their problems.
A Failing Movable Pool Floor System
Upon my arrival, I was met with an odd home-brew moving floor system. In an attempt to reinvent the wheel, the pool builder attempted to create his own moving floor systems. The premise was that ballast tanks would be filled with water to lower the floor and be filled with air to raise it.
In theory, it may have worked, but as with any unproved and untested design, there are always kinks. Testing theories on a wealthy client and working out the kinks on a multi-million dollar pool project, is never the place to learn.
A Poor Choice of Materials
To begin with, the structure was fabricated out of aluminum. Anyone who’s spent time around chlorinated swimming pools knows that aluminum rapidly decays in salt or chlorinated water. The ballast tanks did not have any bulkheads, so the water sloshed from end to end. This caused the floor to list to one side or end, binding it within the pool walls. You can imagine a multi-ton structure wedged within the pool walls. The deck of the floors were finished in Ipe, a hard exotic hardwood. However, after submersion in water, the wood becomes gray, slimy, and slippery.
To make matters worse, the builder failed to recess the incandescent lights and wall fittings. So the shifting floor structure would sheer off the glass lenses and fittings. In a futile attempt to keep the multi-ton structure aligned, the builder cut guide tracks into the walls and installed roller wheels. Again, the forces at play here grossly exceeded the bolt-on wheel assemblies.
A Laundry List of Problems Unfolds
The moving floor in the spa was another disaster. The mechanism was a scissors lift, driven by a hydraulic ram. The builder sourced his hydraulic ram from a local tractor supply store. Over a few quick months, the leaking ram created an oil slick atop the spa. Needless to say, the cast iron ram began to corrode within the chlorinated water.
Once I began to evaluate the hydraulics, electrical, and moving floor systems, it became apparent that the entire project would require a substantial renovation in order to be safe, functional, and code compliant.
Out With Old Pool Floor & In With The New
I partnered with a local contractor, Shawn Hossack of Panorama Builders. Together we came up with a plan to remove the dangerous floor system and install a new fully proven and engineered system. Though we obtained bids from a number of manufacturers, we settled on systems from Hydrofloors – Twinscape Group. Their technical support and proven track record made the client’s choice simple.
The Scope of Work
The interior of the pool & spa was determined to be not completely plumb and true. The only means to correct these deviations would be to render them with mortar and tile them. First, the failing Eco-Finish would have to be removed from the walls, the walls roughened, and prepared for waterproofing.
Since winter was approaching, the decision was made to tent the project under a 100-foot by 50-foot tent and pump in 2,000,000 BTU of heated air 24/7. Over the winter months, the exterior temperature dropped to below -18ºF with the wind chill. Meanwhile, the interior temperature remained a comfortable 60ºF! The cost to operate the diesel heat exchanger and blowers averaged $10,000 a month.
To get the exact contours from which Twinscape could begin fabrication, the crews at Panorama tiled the top 3 feet of the pool in order to generate a 3-D model of the interior.
Since the walls are supposed to be perfectly vertical, these 3 feet would be a representation of the entire pool depth. From this model, Twinscape was able to begin fabrication, while progress was being made on tiling the pool.
The spa wasn’t quite deep enough to accommodate a properly designed scissors lift. We remedied this by raising the spa walls 18 inches and replumbing the jets. Once the concrete had cured, the tiling of the spa began in parallel with the pool.
The clients chose a beautiful blue tile from Interstyle. The hydraulics and mechanical systems were corrected to the best possible conditions without demolishing the decking and totally re-piping the pool and spa. Some pumps were eliminated and their pipes were re-purposed in order to reduce the line velocities on the remaining pumps. Some drains were converted to returns and unblockable drains and sump were installed. The ineffective skimmers in the catch basin were removed and their suction pipes were connected to the basin floor drains. Water chemistry management systems were installed to eliminate corrosion of the new floor systems.
During demolition, we discovered many electrical and bonding deficiencies. The incandescent lighting was converted to strip lights from Hydrolume and proper j-boxes and conduits were installed.
To eliminate the fall hazard over the vanishing edge, we partnered with Reynolds Polymers to fabricate and install an acrylic railing system. The panels were set into a channel within the floor. So, regardless of the height of the floor within the pool, there will always be a railing of sufficient height to protect pedestrians and bathers.
All in all, the repairs to the project took almost 20 months. The ensuing lawsuit resulted in a jury trial and a judgment of $4,750,000 – to date, the nation’s largest judgment in a residential pool construction defect case.
The Rise of pH
Is your swimming pool pH rising and you don’t know why? Learn how to prevent the rise of pH in your pool with these two proven methods.
pH is a symbol for the power of hydrogen. Any chemical that contains hydrogen is considered an acid. There are weak acids and strong acids. Muriatic acid is also known as hydrochloric acid. Muriatic acid is made by taking hydrogen chloride and dissolving in water. This produces hydrochloric acid which is known as a strong acid because it has a high percentage of hydrogen. The term “muriatic” means “pertaining to brine or salt” since it originates from the production of pure chlorine combined with hydrogen. When hydrogen chloride is dissolved in water you have hydrochloric acid. The main takeaway here is the presence of hydrogen. A high percentage of hydrogen ions in pool water will lead to a lower pH.
There are base or alkaline chemicals such as soda ash (sodium carbonate) or baking soda (sodium bicarbonate). These are salts that contain a higher percentage of hydroxyl ions over hydrogen and therefore will raise the pH. The formation of hydroxyl ions from the addition of soda ash leads to the consumption of hydrogen which drives the pH up.
The Unintended Side Effect of Modern Pools
Pools now are designed with waterfalls, fountains, negative edge, and raised hot tubs. The latest system designs include SWG saltwater generators, ozone, and AOP Advanced Oxidation Process. All of these new items offer a plethora of benefits from better-sanitized water to the peaceful ambiance of a backyard water oasis.
These new trends all have one thing in common. They create either aeration or turbulence of the water that leads to the increase of pH. Swimming pool water contains a collection of chemical species. Water balance species include carbonate ions (CO3-2), bicarbonate ions (HCO3–), carbonic acid (H2CO3) and carbon dioxide (CO2). Normally, all of these exist in equilibrium.
Aeration and Turbulence Raise the pH
All of the devices named will cause the pH to rise. Here’s how; When air is forced into water it breaks the equilibrium of CO2 between the air and water. This is a violation of Henry’s Law which states that the amount of gas in a liquid is in proportion to that of the same gas at the surface. The first phase here is that aeration causes the water to off-gas CO2. This upsets the equilibrium of all the species and causes the consumption of hydrogen. When hydrogen is consumed the pH goes up. Aeration and turbulence are present in ozonators from the bubbling of the O3 gas. In saltwater generators, chlorine gas is produced at the positive cell and sodium hydroxide and hydrogen gas are made at the negative cell. The bubbling from these gases is enough to cause turbulence and increase pH. Obviously, when waterfalls or fountains run continuously there is high aeration which leads to increased pH. Raised hot tubs that spill over into the pool will increase pH due to the aeration from the jets and the turbulence of the overflow from the hot tub to the pool. High negative edge drops also create turbulence that increases pH.
Two Ways to Ease The Rise in pH
The ideal standards for pH are between 7.4 to 7.6. High pH can lead to:
- Lowered percentage of active killing agent from chlorine (with or without CYA)
- Scale formation
- Metals will stain at pH of 8 or above especially copper
- Cloudy water
- Reduced Oxidation Potential Reduction ORP
There are two very simple ways to reduce pH increase.
One: Keep the total alkalinity at a target between 70-80 ppm. High total alkalinity can be lowered by 10 ppm using 25.6 fl.oz. of muriatic acid in 10,000 gallons of water. Be sure to test and account for the cyanuric acid CYA that contributes to total alkalinity. If there is CYA present in the pool over 50 ppm 1/3 of the CYA reading must be subtracted from the total alkalinity test to get the correct carbonate alkalinity. With the total alkalinity lowered by acid to between 70-80 ppm the pH may decrease below 7.0. You can aerate by using the running waterfalls etc. in the system to raise the pH to 7.4-7.5 without having any effect on the total alkalinity. The pH can be managed better at these levels and less acid will be needed to keep pH down. The LSI can be helpful here as well. Where total alkalinity is kept is also based on the primary sanitizer used. Trichlor is an acidic form of chlorine so it will lower both pH and total alkalinity. In this case the alkalinity can be maintained at 80-90 ppm. If using cal-hypo or liquid chlorine 60-70 ppm is preferred.
Two: Add borates to slow down the rise of pH. Adding borates at a level of 50 ppm will help considerably to slow the rise of the pH in pools with water features or devices that produce turbulence. Adding borates can help conserve the amount of muriatic acid needed to control a rising pH.
Everything related to water is about balance. Proper management of total alkalinity and the addition of borates can help to restore balance and slow down the rise of pH in pools with high aeration.
Contractors and Builders
Avoiding The Negative Spiral
Avoid the negative spiral by adhering to 4 fundamental principles.
A lot of builders compete on price and operate on narrow margins. This leaves little revenue to perform warranty repairs or to correct errors made during construction.
These builders oftentimes rely on the profit from the next job to fix mistakes from the last project. As the economy slips into a recession, these revenues shrink even more and the pool of funds available to remediate mistakes dries up.
Delays in performing repairs increases and customer frustration grows. As customer complaints intensify, the quantity of lawsuits rise.
The solution is simple, but multi-fold:
- Fix your errors and warranty call backs promptly.
- Maintain open lines of communication – don’t ghost clients or feed them BS.
- Increase the contingencies built into a project. Set them aside into a separate account, and don’t spend them upon each project completion.
- Improve quality control and reduce errors & mistakes.
Now, more than ever, as the economy constricts, clients will become more frugal and conscience of what is occurring in their yard. They will be less tolerant of delays and excuses.
Avoid the vortex.
This was a post originally published on Facebook that received an enormous response from peers within the industry.
Thoughts from some of my followers:
I don’t play the race to the bottom game to get the job. I have my margins and if someone goes cheap, they can have the job. If I don’t make what I need to, I walk away.Michael Koenig
Another way to remediate this is to ensure that your profit margins are adequate enough that you don’t have to rob Peter to pay Paul. If you’re actually performing quality work, the customer should be charged accordingly. Quality work costs money; most reasonable customers understand that. Michael Calore
Great advice. As a a 40+ year pool builder I wish just one of ex employees that decided to go into business for themselves would take the time to learn the business. I wouldn’t have made a career of repairing (and being paid well) for repairing others mistakes. JA GROW
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