Category Archives: Design

Pool Chemical Room Recommendations

One of the specialty areas of aquatic facilities is the chemical room. These rooms are areas of the facility that are subjected to aggressive materials and more restrictive building code requirements. The International Building Code (IBC) describes a high-hazard occupancy as one “that involves the manufacturing, processing, generation or storage of materials that constitute a physical or health hazard in quantities in excess of those allowed.” High-hazard group occupancy ratings may require sprinkler systems, non-combustible floors, storage containment requirements and fire ratings.


Facilities that include a large body of water or more than one body of water can easily exceed the exempted quantity of chemicals allowed in the code. Designating the pool chemical storage rooms as a high-hazard group (H-2 or H-3) occupancy rating will allow for larger quantities of chemicals to be stored.  Chemical storage requirements are a function of the type of chemical stored. Anticipated pool chemical usage should be reviewed against available storage with a minimum storage quantity covering one week of use.


Common pool chemicals include the following:

  • Sodium Hypochlorite (liquid chlorine) is classified as an irritant with a sodium hypochlorite concentration of less concentration of less than one-percent. It is non-flammable and low in hazard. Some codes limit storage to 500 gallons or 1000 gallons.
  • Calcium Hypochlorite (table chlorine) is classified as a corrosive class three oxidizer. It is flammable and high in hazard. Some codes limit storage from 2 to 200 pounds in a single location. If this maximum quantity is exceeded, this space will need to be classified as a high-hazard group H occupancy.
  • Bromine (BCDMH) is classified as a corrosive, either class one or class two oxidizer. It is not flammable in and of itself, but it may ignite combustible materials in which it comes into contact. As such, it is identified as a hazard. Some codes limit storage to as much as 1000 to 4000 pounds in a single location. Typically, occupancy fire ratings of the room in which it is stored and used is two hours. Some jurisdictions may require that the space be provided with a qualified and approved sprinkler system. Additional storage of Bromine can be provided in a high-hazard group H occupancy room if the building has such a room.
  • Muriatic Acid (hydrochloric acid) is classified as a corrosive. Muriatic acid is highly reactive liquid acid. It must be stored separate from oxidizers and in a well-ventilated space. The IBC allows for up to 500 gallons of a corrosive to be stored and used before needing to reclassify the storage space as high-hazard group H occupancy.
  • Carbon Dioxide (CO2 – carbon dioxide liquid) is a liquefied gas which is colorless and odorless. CO2 must be stored in accordance with all current regulations and standards. The stored space should be well-ventilated.


Every pool chemical room requires mechanical ventilation at a minimum rate of one CFM per square foot of floor area over the storage area, as stated per IBC and IFC or 10 air changes per hour, whichever is more restrictive. Confirm with local codes and regulations if more stringent standards are required. Fumes and vapors shall be vented with exhaust taken per IBC and IFC recommendations. Return inlets for chlorine rooms shall be located low in the space as chlorine vapor is 2.5 times heavier than air and sinks to the floor, and return inlets for muriatic acid shall be high as acid vapors rise. In cold weather climates, heat must be provided to keep the room at a minimum temperature of 40°F to prevent freezing.


Understanding the challenges and provisions associated with pool chemical rooms allows for the proper design and construction of these specialty areas. Although these rooms are a small area of the facility, they are subjected to the harshest conditions. Typically, if a facility has great-looking chemical rooms, you can be sure the rest of the facility looks great too.


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pH Buffering

The world of pH buffering is changing. For years, pool operators had to choose between using CO2 or muriatic acid to adjust the pH of their pool. As time went on, some sophisticated operators installed both systems on their pools and manually switched between them to maintain the desired level of total alkalinity in the pool. And that was where the industry remained for many years, until now.

We live in a world where chemical controllers can function as building automation systems for the pool. This functionality has helped cause a major evolution in the world of pH buffering. Owners can now install a dual system of CO2 and muriatic acid that allows the controller to demand either chemical on a “time-based proportional feed system.” This simply means that the owner can control (through the chemical controller) how much CO2 is fed in proportion to acid. This is currently the only way to automatically control total alkalinity, as there are no chemical probes or other ways to digitally monitor it readily available. But, this technology allows for a pool’s total alkalinity to be maintained nearly automatically.

What is Total Alkalinity?

Total alkalinity is the measure of all dissolved bicarbonate (HCO3-), carbonate (CO3-), and hydroxide (OH-) ions.  It acts as a pH “buffer” in pool water to prevent large changes in pH. Low total alkalinity allows for rapid pH change, which makes it more difficult to control pH levels. Ultimately, this can contribute to corrosion in the pool. On the flipside, high total alkalinity makes adjusting the pH difficult, resulting in cloudy water and scaling. It’s important to find that total alkalinity balance to ensure the longevity of your facility.

CO2, as a pH buffer, raises the total alkalinity, while muriatic acid lowers it. If the source water has high total alkalinity (over 70 ppm), muriatic acid is recommended over CO2. Total alkalinity levels should be tested in all source water, along with calcium hardness and pH.

Industry standards typically recommend a total alkalinity between 80 and 120 ppm depending on the type of sanitizer used in the pool water.

Muriatic Acid

Muriatic acid is a 31.5% solution of hydrochloric acid typically used as a pH-buffering chemical. It’s usually automatically injected into the pool recirculation system in small amounts. The acid reacts with the sanitizer, thus counteracting the pH, and raising the effects of the sanitizer. In the pool, it will lower pH and total alkalinity.

Carbon Dioxide (CO2)

CO2 is an alternative pH-balancing chemical that is effective with “soft” source water. CO2 is a liquid, but when vented, it becomes a gas. It can be injected into the pool via a sand stone or mazzi injector. CO2 tends be more user-friendly and safer to handle than muriatic acid.

Carbon Dioxide is a liquefied gas that is both colorless and odorless. There are many regulations and standards surrounding its storage, so it’s important to remain aware of these. Tanks must be properly secured and segregated from any areas of activity, and the stored space should be well ventilated.

Adjusting Total Alkalinity:

Increasing total alkalinity involves adding one of the following chemicals to the pool: sodium bicarbonate, CO2 or baking soda (dry). Decreasing total alkalinity involves adding either sodium bisulfate (dry acid) or muriatic acid (liquid). When lowering total alkalinity, it is common to “slug the acid.” This means adding acid (liquid acid or pre-dissolved dry acid) to the deep end of the pool in a concentrated area.

Do You Need Both Systems?

The short answer: yes. Monitoring and controlling total alkalinity is an important part of maintaining water clarity. It’s something that should be tracked daily, and constantly kept in check. The same goes for pH and sanitizer levels.

The issue that we see with pools that utilize a single system is pool operators having to constantly add sodium bicarbonate or acid manually. As pool operators will tell you, this is no fun task, especially since it allows for inaccuracies. Dual systems eliminate the need to manually add either chemical and ensure levels are accurate.

We have seen some operators create a sodium bicarbonate slurry and setup a chemical feed pump to add it to the pool. However, this is still a manual system controlled by the operator, as the operator decides when to turn the system on and off based on total alkalinity readings. Additionally, this is not seen as an industry standard.


The perceived cost for dual systems is relatively small on a year-round pool. Most year-round pools are built with a chemical controller that could easily have this capability. The relative cost add is typically negligible when understanding the cost owners face buying other chemicals to maintain total alkalinity throughout the life of the facility. The difference: a dual system is part of upfront capital cost, and manually adding chemicals is part of operational costs.

Not Quite Industry Standard

While this idea is starting to take shape, it is not something that has been developed as an industry standard. The first of these systems should be installed in the summer of 2017. After these first systems are installed, it will be critical to collect feedback to help determine the potential for the system to be standardized.

If your chemical controller was installed prior to this timeframe, it will take some manipulation for the controller to be able to have this capability. However, some brands and models just won’t be able to. Most chemical controllers are actually built for a specific project. So if you are looking to add this feature, communicate with your aquatic engineer or chemical controller manufacturer to determine the best way forward.


Backstroke Flags

The sport of swimming continues to grow and with that we are seeing an increasing amount of television coverage. From the Olympic Games to the NCAA Championships, swimming fans can now tune to their local sports station and watch the meet. With that in mind, it is particularly important that we, as pool designers, continue to adapt to ensure that the pools we create lend themselves well to being filmed, while also continuing to provide the fastest and most competitive environments.

For instance, a growing trend involves removing backstroke flags when not in use. This provides a better view for spectators and creates a clear path for television cameras to capture the action. Designing with this trend in mind means altering backstroke flag and post specifications to accommodate cameras. For instance, backstroke flags and posts that are designed to be easily removed or quickly adjusted to prevent sagging might take precedence over another product. Or it may be that flags and posts that are more aesthetically pleasing on camera need to be selected. A designer’s ultimate goal should be to ensure swimmers’ stroke counts don’t change from warmup to race, regardless of the flags being removed or adjusted during the meet.

Backstroke flags come in two types of materials: nylon and vinyl. Nylon flags can be used for both indoor and outdoor installations, and can span up to 60 feet (eight lanes). However, due to their weight, they are not recommended for larger spans, as they can sag and cause deflection in posts. Vinyl flags are generally more durable, but are recommended for indoor use only. They can span lengths of 100+ feet and can be used for 50-meter cross course purposes. Vinyl flags are more attractive, especially when identification and logos are used. Counsilman-Hunsaker makes sure to supply its facilities with the appropriate backstroke flag dependent on pool type, pool configuration, and aesthetic appeal.

While backstroke flags are important, so are the stanchion posts and cable that support them. Counsilman-Hunsaker recommends 8-foot backstroke stanchion posts. These posts are designed to support the flags, while also allowing them to be removed for filming purposes. Anchors are also often used for various course configurations to allow flags to be moved when altering course setup. Counsilman-Hunsaker also recommends utilizing a stainless-steel cable with a take-up reel and ring end fitting on each respective end. This cable allows for the precise tightening of backstroke flags, and provides the necessary support to reduce sagging.

As the sport continues to evolve, we hope to partner with competitive swimming leaders to ensure owners are educated and receive the best products when building new aquatic facilities. As designers, it is important to consider the little details that can make a pool stand out for a growing audience of spectators.



Depth Markers and Warning Signs

Depth makers and warning signs are one of the most important aspects of pool design. Depth markers and warning signs allow swimmers on the pool deck, as well as swimmers inside the pool, to know water depth. Knowing if the water is of a safe depth is critical information for swimmers looking to dive in.
In the United States, every state has its own health code with a standard approach on depth markers and warning signs, and how they should be placed in and around the pool. With that being said, Counsilman-Hunsaker implements its own standard when it comes to the layout of depth markers and warning signs on our pool designs. This standard is one that complies with all state health codes in the country, as well as the Model Aquatic Health Code.

Counsilman-Hunsaker’s standard states that all depth markers and warning signs on the deck shall be either slip-resistant tile or epoxy paint. It is expected that pool decks will end up getting wet, and wet tile can be very slippery. The slip-resistant tile and epoxy paint helps to prevent swimmers from taking a spill on the pool deck.
These deck markings should also be in contrasting color to all surrounding field tile. If the deck markings are the same color as the field tile, they can become camouflaged and overlooked. To keep this from happening, we have the contrasting color specification so the water depth number is clearly visible to all swimmers.
Every state has its own spacing requirements as far as depth markers and warning signs go, though the majority require both to be placed every 25 feet. Some states require that depth markers only need to be placed at the shallowest and deepest points and at every break in slope, while there are more stringent state codes that require the depth markers to be placed at the shallowest, deepest, every break in slope, and at every two feet of change in water depth. To keep all 50 states satisfied, we follow the most stringent codes when placing our depth markers. Depth markers are placed every 25 feet, at the shallowest and deepest water depth, at every break in slope, and at every two-foot change in water depth. Warning signs are also placed every 25 feet from the five-foot break to the shallowest point of the pool. The only thing left for us to do is adjust the placement from 25 feet to 20 feet depending on the local state code for the state we are working in.
As for the “No Diving” warning signs, 49 states require them to be placed from the five-foot break back to the shallowest water depth of the pool. New York is the only state that requires the warning signs to be placed from the eight-foot water depth back to the shallowest water depth.
Being aware of the various restrictions associated with depth markers and warning signs is vital to ensuring the safety of pool-goers everywhere.

False Start Ropes

A false start/recall rope is a rope that stretches across the width of competitive racing pools. It stops swimmers who were unaware of a false start. They’re specifically designed to get the attention of swimmers to prevent them from exerting unnecessary energy in the case of a false start. Typically, the rope is made of some sort of polymer plastic to prevent deterioration from the water, and includes two floats and two quick-snap connectors with weights. The rope is typically located about halfway on yard pools and about 50-feet from the starting end on meter pools.

Counsilman-Hunsaker has continued to include false start ropes in all of our competition facility designs, per National Governing Body (NGB) requirements. All major governing organizations’ requirements surrounding false start ropes can be seen below:

USA Swimming: A device to recall swimmers shall be provided. If a recall rope is used, it shall be placed at the mid-point of the course in long course facilities and at the turn end backstroke flags in short course facilities.
International Swimming Federation (FINA): False Start Rope may be suspended across the pool not less than 1.2 meters above the water level from fixed standards placed 15.0 meters in front of the starting end. It shall be attached to the standards by a quick release mechanism. The rope must effectively cover all lanes when activated.
National Collegiate Athletic Association (NCAA): No Requirement
National Federation of State High School Associations (NFHS): A recall device shall be required for all swimming events at all meets. When a recall rope is used, it should be placed beyond the 15-meter mark.

As lifelong devotees of aquatics for life, we at Counsilman-Hunsaker have been to a fair amount of swim meets over the years. We’ve seen everything from High School meets, NCAA competitions, the Olympic Trials and even the World Championships. And it has been a long time since any of us have seen false start ropes utilized.

With technology continuing to advance at a breakneck pace, over the years we started to see false start ropes usage fade. False starts can now be detected in the starting blocks themselves. False start ropes haven’t necessarily been upheld as necessities. So, our question to you is: does anyone still use false start ropes? Be sure to add where you do or don’t see the benefits in the comments below!