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Meeting & Surpassing Code Requirements

The Ontario and other provincial Building Codes have minimum standards that have been established to ensure that new public pools are constructed to be safe and functional. Following construction, Health Departments are responsible for monitoring and regulating the operation of the pool. The entire content of the code is important, but some items really stand out. For example, strict adherence to the velocity of water moving through suction fittings like the main drains is really important. The velocity of water through main drains is dictated as not to exceed 1.5 fps (feet per second). This low velocity helps decrease the possibility that people might become entrapped or entangled by the main drain fitting.

 

Another really important factor is the turnover rate of the pool. For Class ‘A’ pools (a pool to which the general public is admitted), the entire volume of the pool has to be filtered and chemically treated every four hours. This ‘turnover rate’ provides some assurance that the pool water will be clean and safe for bathers to use. The Building and Health Codes are very important and have elements that work to ensure pools work really well and up to standards, most of the time. As with most rules, there are some exceptions that should be considered. An important question to consider is: When is it a good idea to do more than what the code calls for?

 

CLASS A & CLASS B POOLS

In Ontario for example, a Class ‘B’ pool (a pool operated on the premises of an apartment building with five or more units, a pool operated as a facility to serve a community of more than five single-family private residences, a pool operated on the premises of a hotel, a pool operated on the premises of a campground, a pool operated in conjunction with, a club or a condominium, a pool operated in conjunction with a day nursery, a day camp or an establishment for the care or treatment of persons who are ill, infirm or aged) is required to be designed in such a way that the circulation system exchanges the entire volume of the pools water once every six hours, or four times per day. Most of the time, this is totally acceptable, but there are times when it is not sufficient. At some resorts for example, the pools are shallow and the volume of water is small. This coupled with a very high usage, warmer water and bathers who may not shower as well as they should (especially children) can create a condition that makes the water quality very difficult to manage. We often oversize the circulation systems with larger than required pumps and filters in this instance and add secondary sanitation systems like UV to help ensure superior water quality.

 

The same is true of a Class ‘A’ pool. These pools are required to be designed to exchange the water in the pools every four hours or six times per day which seems like a lot, but again there are some exceptions. If the pool is a therapeutic pool with a higher percentage of elderly users, or users with either a physical or mental disability, there may be a higher risk of contamination by fouling, making it prudent to exchange the water more often and install UV systems. For pools like this we often design the mechanical system to exchange the water every two hours, or 12 times per day, or more.

 

FILTRATION RATE

Another important consideration is the filtration rate of the pool filter system. In all cases this is calculated by dividing the total flow of the circulation pump by the total surface area of the pool and is expressed as GPM/FT2 of filter area. For sand filters, most manufacturers call for a filtration rate of no more than 15 GPM/ FT2. For a pool that has a flow rate of 450 GPM, the total sand area should be no less than 450 GPM/ 15 GPM/FT2 = 30 FT2. This square footage can be achieved by either using one or two larger horizontal or vertical filters, or a ‘battery’ of smaller filters. Is a filtration rate of 15 GPM/ ft2 always enough? For a lesser-used pool with a lower-risk user, and a low bather load, the answer is probably yes, but in instances where there is a high bather load, it may make sense to lower the velocity of water through the filter to improve filtration even more. Sometimes it makes sense to oversize the filter so that the filtration rate is more like 12 GPM/ft2. The same thing can be done with other filter media like cartridge filters or DE (diatomaceous earth) filters. 

 

UV SANITATION SYSTEMS

UV is a secondary sanitizer that effectively renders most bacteria unproductive (and therefore safe) as water passes through the device. UV units are not required by code for pools (UV is required for splash pads) or spas, but may be a really good idea to install anyway. Some bacteria are resistant to chlorine or bromine and can become the source of an infectious condition that can make swimmers sick. This can result in a severe and widespread illness outbreak that could have long term effects or even cause the death of a vulnerable individual. There could also be legal implications for the owner/operator of the pool. Even though the codes do not require it, putting UV systems on a high bather load or high risk pool is a smart and proactive change to make.

 

Finally, the codes are an effective way to improve the overall safety of pools across the community. As with all rules and regulations, not every scenario can be addressed. It is best to look at the particular conditions surrounding your pool and design it appropriately. Since there is no specific  ‘rule book’ to help you decide when code requirements should be exceeded, it is best to consult an aquatic consultant or pool builder who has a long record of experience with a variety of public and private pools. These experienced companies will help you design, build or upgrade a pool that is safe and fun for your clientele.

 

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Understanding Pool Filtration & Filter Media

Pool water filtration is one of the most important aspects of a swimming pool. For obvious reasons, it is imperative that the water be clean and clear. Swimmers and lifeguards require this crystal clear water for several reasons, whether it be for swimming laps, knowing when to start a flip turn, or being able to see all of the pool patrons clearly in order to effectively monitor the pool. Furthermore, the water needs to be clean and free of bacteria so that swimmers do not leave with an illness. While there are many systems that work in conjunction with a pool filter to help keep the water healthy, the physical pool filter, which is available in varying styles and options,  is the focal point in providing clean, clear water. 

 

In most cases, pool water is pushed by the filtration pump through the filter system. Other systems operate using the pump on the other end of the system where it can pull the pool water through the filtering system. Either way, what happens is essentially the same – as water passes through the filter media, physical dirt and bacteria are removed, and clean water continues from the filter through the remainder of the recirculation system for further treatment, and returned to the pool. 

 

The style of filter, along with the media being used, will determine the effectivness of the filtration system, as differing types of filter media actually filter different sizes of particles out of the water.

 

#20 SILICA SAND

The reason that pool filters use #20 silica sand (also known as 20 grit or 20 grain, 0.45-0.55 mm sized granules) is that it is small enough to filter out micro bacteria, yet large enough that it doesn’t get pushed through the whole plumbing system and cause other problems. In addition, larger granules are unable to filter the small bits of dirt and bacteria that it is intended to. #20 silica sand can filter out particles down to 20-40 microns in size. As water passes through the sand (which is essentially a really small stone, which is jagged on all edges if looked at through a microscope), the jagged edges catch tiny dirt and bacteria particles, eliminating them from the pool environment.

 

Depending on various factors (bather load, bather cleanliness, etc.) sand filters need to be backwashed every so often to clean the sand. If the sand filter is not maintained, it will stop filtering as it is supposed to. Backwashing is completed by running water through the system backwards to release all of the dirt and bacteria that has been caught by the sand, and must then be removed from the filter tank.  When the water being discharged is clear, you are finished backwashing. Most filters have a sight glass so operators can physically see the dirty water at the beginning of backwashing eventually turn clear when the process is done.

 

Sand is the oldest and most commonly used filtration media, because it is effective and one of the most cost friendly options. However, after many cycles of filtering and backwashing, the granules become rounded, eliminating their filtering capabilities. The sand should be changed approximately every 5 years, depending on usage and backwashing frequency. 

 

ZEOLITE

Zeolite is an all-natural product that is gaining popularity in the pool industry. It is about half as dense as #20 sand, meaning you can use about half as much as what is recommended for the filter. For example, if your filter requires 100 lbs. of sand, you would only require about 50 lbs. of zeolite. This type of filtration media is a bit more expensive than sand, so there will be a higher upfront cost. With the ability to filter particles down to 5 microns, Zeolite is comparable to a D.E. filter, and better than sand, though D.E. filtration systems are much more expensive than a sand filter system charged with a zeolite media. Zeolite lasts about the same amount of time as sand with regular use, which is approximately 5 years. 

 

CRUSHED GLASS

Crushed glass is a new addition to the filter media family. Made from recycled glass (good for the environment) that is crushed to the same size as #20 sand, it filters using the same principles as sand. In comparision to sand, crush glass lasts longer (approximately 10 years) and can help in removing micro particles with its negative charge. When using crushed glass, more of the filter media is used for filtering because it utilizes more of the filter tank, as opposed to sand which typically only uses the top four to six inches. This means there is a shorter backwash time, saving more precious water. 

 

DIATOMACEOUS EARTH (D.E.)

Diatomaceous Earth (D.E.) filters the water very effectively, down to two to six microns, however they are more expensive systems and take up a larger footprint in the mechanical room. D.E. is tiny fossilized skeletons of sea plankton that are coated onto a grid of filter elements that sit in a tank where the pool water passes through. The water can either be pushed or pulled through this system.  D.E. is considered carcinogenic, and proper handling and storage techniques, including protective gear and breathing protection, must be adhered to. D.E. filters are able to be backwashed for cleaning, but the media is lost in the process, and needs to be periodically replaced. D.E. systems do not eliminate chloramines which cause the chlorine smell commonly noticed at an indoor pool, so using a UV system is strongly recommended in order to eliminate them (a reccommendation for all pool filters). 

 

REGENERATIVE FILTERS

Regenerative filters are another new option in the pool market. They also utilize D.E. or a synthetic substitute, however are a bit more complex in their design. In a traditional D.E. filter, only the channels and depressions of the surface of the filter media trap particles. The underside of the D.E., the side attached to the grid, has a reduced ability to filter. In a regenerative filter, the media is held on multiple tubes, or “fingers”, that are periodically “bumped”, causing the filter media to fall to the bottom of the tank. The filter media is then redistributed, allowing unused sides of the media to be used for filtration as well. Regenerative filters offer a large amount of surface area with a relatively small footprint and are often toted for their water saving qualities due to the reduced need for backwashing and D.E. replacement. The water savings may or may not offset the cost of these units, therefore your individual return on investment should be evaluated before purchase.

 

Thanks to several innovations and advancements in technology, there are many options available when considering pool filters, and filtration media. It is important to consider all of the factors specific to your project when choosing a filtration system, or to at least understand what you want and don’t want when planning with the pool designer that is working on your project. You want to have the right filtration system and media for the facility to ensure it is operating in the most economical way.

 

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