Anti Entrapment Standard Updates – 2021

One of the most comprehensive resources is this YouTube video.

To summarize, previous anti-entrapment cover manufacturing/testing standards including ASME ANSI/APSP-16 2011 have been updated with new criteria for approving the maximum flow and sump compatibility. Contact our office for more information or to request assistance in determining which retro-fit cover options are optimal for your pool.

Alberta COVID-19 Relaunch Info (Sept 2020)

The province has given the green light for re-opening of indoor & outdoor whirlpools, hot tubs, dry saunas & steam rooms!

As always, stay safe and follow all recommendations & guidelines.

For additional information, please see below:

The effect of CYA on Free Chlorine

One piece of pool folklore that ‘floats’ around the industry and becomes a conversation point in the busy summer outdoor pool season relates to the degree to which CYA (stabilizer) reduces the effectiveness of free chlorine. When added at an appropriate dose, CYA prevents the rapid deterioration of free chlorine in the presence of UV light from the sun so it’s still available as an active sanitizer. There is a very sensitive correlation between the increasing level of CYA in water and longer time required for chlorine to kill pathogens in the water. The Centre for Disease Control (U.S. Department of Health and Human Services) recommendation is only use unstabilized chlorine for a fecal contamination response and reduce CYA to below 15 ppm to deal with diarrheal incidents. 50 ppm is the maximum limit set in the AB Pool Standards.

The term ‘free chlorine’ is a measured value that includes both the complete and ‘active’ hypochlorous acid compund (HOCl) and the lesser effective hypochorite (ClO). The pH has a significant role to play in how much ‘active’ HOCl is present vs the less effective ClO. In the world of pool water treatment, we need fast kill times so it’s critical to have most of our free chlorine as HOCl. It’s important to note the key concept here is both compounds register as ‘free chlorine’. If we take the analysis one step further, we can calculate active chlorine from free chlorine to take into account other chemistry variables. This is where we can elevate our understanding and make factual comparisons of active chlorine levels that factor in the effect of pH and CYA on the disinfection capacity of the water.

There’s some great data out there from as far back as 1965 showing the effect of different chlorine levels with variable pH & CYA values on kill times but if you want a tool to handle all the math for you, give the free LABCONNECT app or desktop assistant program a download. This app can connect to a PoolLab photometer via Bluetooth but on its own it has a couple useful stand alone features include the ‘Active Chlorine’ calculator.

See below for some sample calculations showing high CYA with a drop in pH (Figure 1 & 2) and the effect of moderate CYA to no CYA (Figure 3 & 4)

Stanley R. Pickens, “Relative Effects of pH and Cyanurate on Disinfection”, Journal of the Swimming Pool and Spa Industry, 6 (1), 6-19, 2019.

Danial L. Harp. Current Technology of Chlorine Analysis for Water and Wastewater. Hach Company, 2002.

Photo Credit: Centers for Disease Control and Prevention

Head to Head – Chemical Dosing Pumps

Positive displacement chemical dosing pumps are a piece of equipment you’ll find as part of almost every pool mechanical system. Hypochlorite, pH adjustment chemicals & filter coagulants are all commonly dosed with one of two types of pump. Both diaphragm & peristaltic pumps have been long established as reliable and effective choices in the pool world. Within each type, there is a wide spectrum of performance factors depending on the brand and model of pump. It would be incorrect to say one type is superior, there are features unique to each that may make one type a better choice for your application. Here are some of the main feature differences:

Diaphragm Pump – Pros

  • A lower cost of ownership is a general perk that can be claimed for diaphragm pumps- assuming the pump is correct for the application (size & material compatibility).
  • It’s not uncommon to run 1-2 years without having to replace parts. Depending on the chemical – simple annual cleaning can be effective for maintenance.
  • Have the potential to pump against very high line pressure (150-250 PSI is common but generally unnecessary for pool applications).
  • Compatible with automatic ‘flush’ systems for insoluble slurry applications (4-5% soda ash).
  • More readily compatible with ‘pulse’ control outputs for true proportional dosing control.
  • Fractional amperage draw means less load on pump drive and external relays. Controller relay failures are almost always on a peristaltic pump.

Diaphragm Pump – Cons

  • Particulate can cause issues with suction check valve seals and loss of prime issues.
  • If an incomparable pump head is used – trapped gas vapours from sodium hypochlorite can air lock the pump head. Auto degassing heads are available for this application but are often overlooked.
  • Lower stroke lengths (<50%) can lead to loss of prime during periods of low use.
  • Requires more skill/knowledge to troubleshoot.

Peristaltic Pump – Pros

  • Easy to prime as long as roller/tube are in good condition so they generally ‘self-prime’.
  • Handles off-gassing and immune to air locks that can cause problems when sodium hypochlorite is dosed on diaphragm pumps without a de-gassing liquid end.
  • Service & troubleshooting is simpler.

Peristaltic Pump – Cons

  • Higher motor amperage load means the motor won’t last as long as on a diaphragm pump. This also adds extra load/stress on chemical controller relays.
  • More frequent maintenance (tubes are generally good for 500 hours).
  • Some models are limited to 25 PSI output.
  • Tube failure can result in a dangerous chemical spill.

Anti-Entrapment Compliance – 5 Common Misconceptions

The 2006 Alberta Pool Standards introduced our region’s the first written requirement for ANSI/ASME approved anti-entrapment covers and reference to other anti-entrapment devices (SVRS).  The world of anti-entrapment compliance has gone through a gradual evolution, adding layers of complexity in attempt to create standards that can account for all the potential entrapment hazards in a swimming pool system.   I could write a full post just on the evolution of anti-entrapment legislation but I’m going to keep this post more focused and practical.

As much as compliance has become more complicated over time, every year the options available on the market grows which makes it easier to come up with solutions to the wide range of installation scenarios that need to be retro-fit to comply with current standards.  It also gives rise to another challenge of staying on top of what is available and the unique installation requirements from each manufacturer.  We have been privileged to consult, supply, install and test many anti entrapment solutions for over a decade.   If you have any questions or need validation of your anti entrapment compliance situation, our ‘Anti Entrapment Evaluator™’ service gives you a custom written report with the relevant details specific to your facility.  Here is a summary of some misconceptions we’ve run into surrounding the issue of anti-entrapment compliance.

Anti Entrapment is only an issue if you have single main drains

In addition to still needing an Anti-Entrapment Plan (AB Pool Standards, 2018), several details need to be considered for compliance.  Simple pool systems with a single circulation pump on the filter system easy to understand, but that changes when you have multiple circulation pumps.   Additional circulation pumps for features (slides/hot tub jets) create a complication with multiple main drains. Compliance will vary depending on how the plumbing connections from each circulation pump are tied to each drain.  Multiple scenarios are possible with varying arrangements of main drains and pumps. We’ve seen ‘creative liberties’ taken and the plumbing doesn’t always end up being how we would assume it to be. Simple example drawings are shown below illustrating that having 2 drains and multiple pumps can be ‘interconnected’ or ‘independent’ (Figure 1 & 2) which greatly changes how compliance is evaluated.  Other relevant details need to be confirmed such as:

  • Confirming flow rates are compliant (max rated flow for each cover is not exceeded as per the 2018 AB Pool Standards Appendix C calculation)
  • Sump depth compatibility with the installed cover
  • Cover fastening is compliant with manufacturer requirements

Having domed or raised drain covers means you are anti-entrapment compliant

Domed style covers are a popular retrofit design option for smaller suction outlet frames, but like having multiple main drains – it doesn’t guarantee compliance.

Having flat drain covers is a sign that new raised/domed covers are required

Newer large area or channel type drain assemblies have the proper anti-entrapment cover certification with the advantage of being flush with the pool floor. This is generally preferable as it eliminates a trip hazard in shallow water and is not an obstacle for pool vacuums. This type of cover still needs to be evaluated for maximum flow allowance and sump compatibility.

Entrapment isn’t a concern because the pumps aren’t directly connected to the pump suction

This misconception involves a gravity supplied suction line and the assumption that there is no entrapment risk without a direct pump connection. The risk of entrapment is higher when a suction outlet is connected directly to a circulation pump, however hazards still exist in a gravity suction system. Entrapment risk includes body suction entrapment (the primary risk associated with the suction force of a pump) but mechanical entrapment (jewellery, swimsuit, accessory snagging the opening of a cover) and limb/hair entrapment (getting a finger into a cover slot but being unable to get it out) are still important considerations. Gravity outlets can still have a significant suction force – remember the tank is filling from gravity at the same speed as the circulation pump is pulling it out of the tank.

Installing a SVRS/Auto Pump Shut Off device is enough.

These devices can help with solving compliance problems on single main drain installations but an approved cover is still required (and flow rate/sump compatibility are still relevant details). Supplementary anti-entrapment devices still require proper covers are installed.

Chlorine Gas Injection – Safe Design Practice

Despite the many hazards, gas chlorine is still an established method for swimming pool chlorination. Chlorine gas is pulled from a pressurised cylinder under vacuum through supply lines. This is the safest way to feed gas chlorine, any break in the gas line results in a loss of vacuum instead of a dangerous pressurised gas leak.

Vacuum is created by water passing through the injector nozzle. The design of which accelerates the water to create a venturi effect that pulls chlorine from the vacuum regulator. The regulator is typically mounted directly on a pressurised gas cylinder. Most installations use two cylinders, with an automatic switch over mechanism for uninterrupted gas supply. A two cylinder system can be set up with multiple flow meters (rotameters) to supply one or several pools from the single source.

Note: The term ‘injector’ is used by some manufacturers, others use ‘ejector’. For simplicity we will use the ‘injector’ to cover all makes/models of gas chlorine injection products.

A vacuum based feed system has the potential to pull chlorine when unintentional vacuum conditions are created in system plumbing. This siphoning effect is most likely to occur when the circulation system plumbing is above the pool water level. A loss of line pressure can result in the lines draining out to the pool (or open filter tank), and the action of this water ‘falling’ out of the pipes can create enough vacuum to pull chlorine gas from the regulator. This high rate dosing of chlorine without water flow is very dangerous; small basins of water can easily be over chlorinated or pure gas can end up in areas where staff and patrons are not expecting it.

Alberta building code requires anti siphon features on chemical dosing equipment installed above the swimming pool. We highly recommend that all swimming pool gas chlorine systems use ‘anti-siphon’ injectors. This feature on an injector means that a vacuum condition will only draw chlorine if there is the presence of water flow & pressure on the injector. Installations with the potential for extreme vacuum (>24” hg) may require an additional vacuum breaker on the plumbing system.

Sample Injector Installation

We recommend one of the following injectors:

• Capital Controls EJ17 Ejector with Anti Siphon Valve Assembly (cannot be used with Evoqua regulators)
• Evoqua S10K Anti Siphon Chlorine Injector (can be used with Capital Controls & Evoqua regulators)

Recommended injector installation practices

1) Pressure gauges on the influent & effluent side of injector greatly assist troubleshooting
2) Inline strainer before the injector
3) Check valve installed on effluent water line (viton or teflon seals recommended)
4) Solenoid or booster pump control should prohibit rapid on/off cycling. Using both a solenoid and booster pump should be avoided.

5) Injector plumbing should be with rigid PVC pipe and unions for ease of maintenance. Flexible plumbing connections can deteriorate and are more likely to leak

Annual Maintenance Recommendations

1) Both manufacturers recommend annual preventative maintenance with designated PM kits
2) Clean the internal nozzle openings
3) Replace check valves that are downstream of the injector
4) Follow manufacturer recommendations for startup and equipment testing upon re-installation


De Nora Water Technologies Gas Chlorination of Swimming Pools Sept 2015
Do Nora Water Technologies Instruction Manual —EJ17 Ejector Sept 2015
Wallace & Tiernan Products S10K Chlorinator for Swimming Pool Installations Nov 1999
Photo Credit

The Clear Issue

Pool water quality isn’t often a topic of discussion you see in the mainstream media but it took the front seat during the Rio Olympics this summer. On Tuesday Aug 9 the 3,725,000 Liter dive pool took the ‘going green’ movement very literally.

As with any current events news topic, the facts were inconsistent at best. Speculation ensued from pool experts everywhere. Sources closer to the event also had some varied explanations. ESPN reported a Rio spokesman explaining it was a “proliferation of algae.”1 FINA offered their own chemistry backed explanation “pH level of the water was outside the usual range.”2 A later statement from the Rio organizers pointed to “a sudden change in alkalinity.”3 A more recent theory was related to hydrogen peroxide being dumped into the pool.4  As any experienced pool operator knows, this sort of problem can be time consuming and frustrating to troubleshoot regardless if we’re talking about an Olympic pool or a small hotel hot tub. Our company has had the privilege of being involved in many water quality problems over the years. The knowledge we’ve acquired from +30 years of solving pool problems has lead us to form a very practical approach to water quality troubleshooting.

Water clarity is always the first thing I notice in a pool, regardless of the color. It’s becoming more common to see operators have inline turbidimeters or portable test kits on hand so that a record of quantifiable clarity measurement (nethelometric turbidity units, or NTU’s) can be maintained. Small changes in the NTU value can warn of deteriorating water quality before a visible problem is detected. Part of the problem with identifying clarity issues is most pools don’t have a good depth of water to properly evaluate clarity and it’s not known how long a problem has actually been developing. Clarity can easily be taken for granted as being ‘ok’ or ‘good enough’. From a safety perspective, it is obvious to want the water to be sufficiently clear so that a distressed or drowned swimmer can be seen. Extreme cases in cloudy water can certainly cause safety and supervision problems but more minor water clarity problems can be the source or symptom of several undesirable issues requiring corrective action. When your pool becomes cloudy to the point that someone notices even a slight murkiness, it should be regarded as an indicator of a deficiency in the pool water treatment process.

If a turbiditmeter isn’t a practical option to have, using a handheld mirror held just below the surface to observe across the length of the pool is a great tool to gauge clarity. Look for a tile marking/pool fitting/ladder etc. as a marker for how far you can see. The farther the distance you look the better the indicator of clarity. Make a habit of doing this daily, try it first thing in the morning and after a busy swim to get a feel for how the water quality changes with varying bather loads. This can also be used as a tool for when to dose a filter aid/flocculent and evaluate other treatment tools.

Persistent clarity issues can also be attributed to a filter performance issue (media condition/filtration speed/equipment failure/valve problem) which can compound with ineffective oxidation (using chlorine alone to disinfect and oxidize bather waste).  In summary, clarity should be the priority. Water clarity is one of the best tools for water quality and should be an operator’s priority. If you wouldn’t eat in a dirty restaurant, why would you swim in a cloudy pool? Clear discoloured water isn’t as much of a concern to me, if the water chemistry is satisfactory there is no reason to worry about the bathers.

In my experience, the most common cause of clear green water is the oxidation of a dissolved metal, such as iron or copper. Too much copper can be the result of overdosing a copper based algaecide, high source water levels or corrosion of copper equipment in the system (such as a heat exchanger).  Iron isn’t as commonly tested for but the problem with iron testing is the iron is not be dissolved as elementary iron in pool water due to the oxidation from chlorine, instead it is dissolved as an Iron(III) complex after being oxidized. This is why it may not detectable with normal iron testing as found in many photometers. The source of iron can be from source water, corrosion of cast iron pool equipment or iron being released from some types of carbon based filter media. The release from media is the result of a corrosive water reaction from low alkalinity and/or low pH inside the filter tank.

Part of the solution involves taking all the pool specific factors into consideration and doing some detective work. The trouble with trying to understand the Rio pool problems is we don’t know anything about their operation. The regulations and standard practices for running pools can vary from country to country. For example, our colleagues in Austria & Switzerland must maintain free chlorine levels at 0.2 – 0.6 ppm as it’s generally accepted that higher levels of chlorine create unhealthy pool air (they can get away with this because they have very high standards for filtration and circulation). I don’t know anything about what is being used for filtration and sanitizing chemicals at the Rio Olympic pools so I am going to withhold from throwing another theory out there. If you have a clarity/colour problem that is persistent or have an interest in perusing technologies that provide better water quality with less chlorine, please don’t hesitate to contact us.

1. Green pool? Algae said to be cause for change. (2016, August 10). Retrieved August 30, 2016, from

2. Dillman, L. (2016, August 27). Retrieved August 30, 2016, from

3. Lyall, S. (2016, August 10). Another Pool Turns Green; Chemical Imbalance Is Blamed. Retrieved August 30, 2016, from

4. Lyall, S. (2016, August 13). Rio Olympics: Green Pools Caused by Hydrogen Peroxide Dump. Retrieved August 30, 2016, from

Photo by NBC

Combined Confusion – Part 1

When troubleshooting pool chemistry issues related to fluctuations and inconsistencies, I often joke that the only way to keep pool chemistry in perfect balance is to not let anyone use it. When the heat is off and no bathers are present, pools almost take care of themselves. Trace amount of chlorine give very high ORP values (the measure of the quality of disinfection) and very little chlorine is consumed to maintain those levels. Not only is the chemistry stable but the water itself stays in impeccable form. Incredible clarity and no offending chlorine (or ‘pool’) smell are the two healthy water qualities I look for in a well maintained pool. Being around commercial swimming pools for 10+ years now I can tell a lot about a pool just from the smell and a quick look through a true depth of water (the length of the pool, not looking top down – hold a mirror on the pool wall and evaluate how well you can see the other side). I don’t need to do a water test or walk through the mechanical room to know if the pool water is being properly maintained or not. My conclusion is that it takes a trio of good equipment, good procedures and good operators to deliver healthy pool water.

In Alberta, a measurable residual of free chlorine is required at all times for a pool to be open for public use. Although chlorine is highly toxic, in small quantities it is a highly effective as a disinfectant. Disinfection is important to keep your bathers healthy and free from the pathogens that can potentially inhabit the water (the worst of which are those that are introduced via fecal matter, hence the precautionary actions taken in the event of a fecal release). As good as chlorine is at disinfection, it’s by no means perfect. Chlorine is not a desirable oxidizer. The oxidation of organic material in the water (urine, sweat, dead skin, hair, cosmetics etc.) results in a reaction that forms some type of combined chlorine. (WHO Chlorination Concepts Fact Sheet 2.17) To say combined chlorine is formed grossly oversimplifies the matter, combined chlorines can be classified as monochloramine, dichloramine and trichloramine (nitrogen trichloride). The type of combined chlorine formed is dependent on the ratio of free chlorine to ammonia. Simple monochloramines are often present in fill water as the preferred disinfectant for potable water distribution lines. Monochloramines don’t have the odour problems associate with dichloramine and nitrogen trichloride. In drinking water, the independent dosing of chlorine and ammonia is controlled to ensure correct rations are present so only monochloarmine is formed (EPA Guidance Manual – Alternative Disinfectant and Oxidants, 1999). Although monochloramine is combined chlorine, it’s not so bad. US EPA allows up to 4.0 mg/L of monochloramine (recommended is 1.5-2.5) for drinking water. Having monochloramine alone is beneficial in a drinking water distribution system for a couple reasons. One is that the residual lasts longer but it also is less reactive than free chlorine and does not as readily form trihalomethane (THM) due to reactions with organic material (WQA Chloramine Fact Sheet, 2014). THMs should be considered the real enemy – not necessarily ‘combined chlorines’. The requirement for quick kill times means we can’t use monochloramine as a disinfectant in pool water (free chlorine is 200x more effective). The US EPA also sets the limit for THM at 0.08 mg/l in drinking water, the limit is 0.10 mg/l in Canada. Unfortunatly, THM testing is difficult due to the volatility of the compound and requirement for high end test equipment so it’s not realistic to expect to test it on the pool deck with current water analysis technology.

To summarize the points made so far, ‘combined chlorine’ is not a specific enough test to tell us if anything is ‘good’ or ‘bad’. The other big take away is THMs are the real concern. THMs are formed from excessive chlorine levels reacting with oragnic material (bather waste), more chlorine = more THM (WQA Chloramine Fact Sheet, 2014). If we were to remove the monochlormaine from the picture, we would have a better idea of the undesirable byproducts that are in the water. Dichloramine and nitrogen trichloride are undesirable byproducts in that they cause greater “swimming pool”- type taste and odor problems when they exceed concentrations of 0.80 mg/L and 0.02 mg/L (respectively). (WQA Chloramine Fact Sheet, 2014).
The problem with our pool industry test kits is the failure to awknowledge these established facts.

The false and wrongly oversimplified chlorine test procedure is very familiar to pool operators:

Total Chlorine = Free Chlorine + Combined Chlorine

As stated previously, the combined chlorine that consists of monochloramine, dichlormaine and nitrogren trichloride is not much use to us. Let’s call this example A; If you have a monochloramine resuidaul of 3.0 mg/l but your dichloramine and nitrogen trichloride reading of 0.0 mg/l, then I would say you have really good water despite a ‘combined chlorine’ reading of 3.0. Example B is less desirable; monochloramine is 0.1 mg/l and 1.0 dichloramine, 0.5 nitrogen trichloride. Although the traditional ‘combined chlorine’ reading is 1.6 mg/l, these measurements are much more problematic because of how much worse dichloramine/nitrogen trichloride are at low concentrations. Example B is what happens during breakpoint chlorination, you have less of the ‘not bad’ monochloramine but the others (plus the THM levels) actually increase significantly.

Unfortunately, there is one more problem with combined chlorine testing. The test starts off good, DPD free chlorine reagent (usually a 2-part reagent) reacts specifically with HOCl which is free chlorine. The next step uses DPD3 (potassium iodide). DPD3 reacts with all oxidizers in the water. If you only had chlorine then the assumption that all oxidizers means total chlorine is correct, but the reality is to effectively run a pool you need a non-chlorine oxidizer. Oxone and Chlorine Dioxide are the most common, and are usually present in the water to help reduce the aforementioned undesirable chlorine reactions with organic material. So DPD3 will test positive for our helpful oxidizers, this further limits our ‘combined chlorine’ test accuracy.

If we were to advance our water test equipment and methods out of the 1970s, we would have to change that equation to:

Total Oxidizer = Free Chlorne + Monochlormaine + Combined Chlorine* + Oxidizer

*This new combined chlorine would be a more accurate depiction of ‘undesirable’ byproducts in the water (dichloramine and nitrogen trichloride) with a recommended value being less than 0.1 mg/l.
In pool water treatment we don’t have the luxury of controlling the amount of ammonia in the water. The outdated theory of ‘breakpoint chlorination’ is based on driving the oxidation process past the point of nitrogen trichloide formation. Hydraulics are a limit that prevent the uniform breakpoint occurring at the same time throughout the basin, but the real problem is that breakpoint increases levels of dichloramine/nitrogen trichloride and THM.

Traditional breakpoint chlorination theory for combined chlorine removal is outdated and inefficient. The problem is the result of undesirable oxidation caused by too much chlorine in the presence of high levels of organic waste, adding more chlorine to fix this is simply throwing more fuel on the fire and accelerating the reactions taking place – not preventing them. To further advance this comparison to a fire (which is also a form of oxidation), we can agree there are 2 ways to put out a fire. On one hand you can help the fire by feeding it so it consumes everything until there is no fuel left and it burns itself off, this is the approach of ‘breakpoint chlorination’ theory. This theory pre-dates non-chlorine oxidizers that have been commercially available for +30 years now. While breakpoint may appear to lower the ‘combined chlorine’ test result, in reality there is less monochloramine but more of the other combined chlorine and THMs. Switzerland and Germany both set limits on THM levels at 0.02 mg/l and to achieve this, they have to set strict limits on free chlorine as well (maximum 0.6 mg/l. Running at higher chlorine levels consistently leads to increased THM formation. It’s not realistic to expect to run under 0.6 mg/l unless you have a filtration system to back it up. Traditional shallow, spherical north american sand filters and pre-coat style ‘DE’ filters would not pass the performance criteria in these countries with strict recreational water quality standards. They rely on true depth filtration (multi-layer deep bed sand filters with optimized flocculation/coagulation) in order to get away with running lower chlorine levels.

You need to decide if your goal is to either feed the fire or prevent it altogether, you will want to consider treatment options that remove organic material from the water and prevent the undesirable reaction from occurring in the first place. The most efficient treatment choices will be those that improve filtration and enhance oxidation without creating more chlorine demand.

Keep watching for future posts in this series, including a detailed examination of available supplemental treatment options and a more in-depth look at combined chlorine testing.

SVRS Testing

SVRS (safety vacuum release system) and Automatic Pump Shut Off devices provide a layer of anti-entrapment protection for pools that don’t have multiple submerged suction outlets.  These devices are designed to disable pump suction (mechanical or electrical disconnects) in the event of a detectable entrapment.  There are several approved devices on the market, it’s important to familiarize yourself with the operation of your specific device.   Most devices require a system test is performed at the initial start-up and anytime system changes are made.  Depending on your device, there may be a requirement to perform periodic function tests to ensure your device is maintains its compliance with the ANSI/ASME A112.19.17 standard.  We strongly recommend you carry out and log periodic testing as it is a practice that many health inspectors are looking for during onsite inspections.   Some pools with multiple pumps may have multiple SVRS devices, it is important to test each device.  Should your device not function as designed during a test, it is very important to close the pool to bathers and carry out additional troubleshooting to resolve the issue.  We can set this service up as a recurring visit with our Evaluator™ program or provide additional training to ensure your team is confident with their SVRS operation and testing procedure.  It’s very important that all staff at your facility are aware of potential entrapment risks around pools and hot tubs.  Anti-entrapment compliance is an ongoing responsibility and requires that staff are knowledgeable and aware of potential hazardous conditions.  If you have any questions or require documentation for your device please contact our office.  See below for some guidelines on testing common SVRS equipment, consult your owner’s manual for full instructions before carrying out any testing.

Vacless SVRS Testing

The Vacless requires monthly testing.  To test, leave main drain suction line valve(s) open 100% and close or plug off all other pool outlets on the pump suction lines.

Simulate entrapment by closing the main drain suction valve(s) that are installed within 2’ upstream of the pump.  The Vacless valve seal (piston) should activate (open).  This allows air to rapidly fill the pump and will cause a loss of prime.  Once activation is confirmed, open the main drain suction valve(s) and the valve seal should close and normal pump operation should resume.  Repeat this test three times, if the device does not perform as described above the pool is to be closed to bathers and additional troubleshooting will be required.

Stingl SR-500 SVRS Testing

The Stingl SR-500 requires testing anytime the settings are changes and recommends monthly testing.  Proper operation of the SR-500 must be verified by restricting flow to the pump while running in any of the normal operating modes (timed, continuous, and remote). Begin testing by covering the main drain sump(s) with a rubber mat. This will cause the pump to pull through the skimmer line(s) only, resulting in a higher operating vacuum. It may be possible to cover the drain and not increase the operating vacuum past the cut-off threshold. In these cases it will be necessary to close the skimmer valve(s) to create the vacuum necessary to create an alarm condition. NOTE: Repeat this test 3 times to verify proper installation.

PSP20 Automatic Shut Off Testing

The PSP Automatic Shut Off device requires testing every time the filters are backwashed or every 7-days to ensure the correct operation and programming of the H2flow Inc. PSP20. Testing consists of closing the pump suction valve causing the pump to dry run. The PSP20 should shut the pump down within 1 second.

On Pool applications with skimmer’s, close the skimmer valves prior to completing this procedure.

Ensure that the Timer has disappeared from The Display

To test the PSP20 for a blocked suction condition, ensure that the LCD display shows window 01

Close the pump suction valve. W ithin 1.0 Second the pump should shut down

The display will show Function Underload

The panel Reset push button Light will be illuminated, showing a blocked suction condition has occurred.

To reset the alarm and to restart the pump, press either the ‘Reset’ or the remote ‘RESET’ push button located on the door of the PSP20

Hayward Stratum SVRS Testing

The Hayward Stratum VR500 performs a complete internal system test during every start-up sequence.  Should anything change with the system design (plumbing changes and/or pump replacement), a test consisting of three simulated entrapments must be conducted to verify proper installation, calibration and operation.

An entrapment can be simulated by partially closing or repositioning a valve, so, that there will be a change in the flow pattern. That is, changing the pattern of flow from the suction outlet (Main Drain) to the skimmer will simulate an entrapment.

Field testing criteria to verify the release of a potentially entrapped bather is three simulated entrapments, in which the VR1000 turns off the pump and vents the suction line within three seconds in each of the three simulations.

Field testing criteria to verify the functioning of the pinched tube function is required. This function determines if the system can determine if the pump is connected to the VR1000 vacuum tube, when the pump is running.

A ball, butterfly or sliding gate valve shall be installed within 2 ft (0.6m) upstream from the STRATUM™ (between the STRATUM™ saddle for the vacuum tube and the protected suction outlet), or a test mat shall be used to cover the suction outlet to simulate an entrapment event.



Equalizer Lines & Anti Entrapment

If we were to discuss major operational changes over the last 10 years in aquatics, it would be hard to think of anything more prominent than anti-entrapment compliance.  As of Dec 2007, the United States federal Virginia Graeme Baker Pool & Spa Safety Act catapulted anti-entrapment risk management to the attention of aquatic operators and health inspectors across North America.  The AB pool standards have been heavily influenced by this American policy change.  When we talk about anti-entrapment, main drains on the pool floor immediately come to mind.  However, anti-entrapment refers to all submerged suction fittings.  This includes vacuum ports and equalizer lines.

Almost all pool fittings sold in Canada are designed and/or manufactured in the United States, it’s very difficult to find any suction fittings on the market that are not compliant.  The reality is most pool main drains in Alberta at this point in time are in compliance, sometimes the compliance can be difficult to assess (we’ve developed the Anti-Entrapment Evaluator™ report to help with this) but as time goes on and our awareness improves we are finding unique situations that are not compliant with the current standards.   Suction lines for jet pumps and feature pumps are often forgot about since there is typically no flow meter present on these systems, the false assumption is that the flow rate on the filter flow meter is telling us everything we need to know.  Another area of trouble is with equalizer lines.  If your pool system has wall mounted skimmer fixtures, there is an equalizer port inside (figure 1).  Manufacturers recommend the rear port is connected to the filter pump suction line and the front port (closest to the pool basin) is connected to a wall fitting approximately 1’ below the skimmer mouth.  If your skimmer has a functioning float valve (under the basket – figure 2), a drop in water level causes the float valve to drop and create a seal that connects the pump suction port to the equalizer port which allows the pump to safely run without cavitation as long as the water level remains above the side wall equalizer fitting.  At this time, the equalizer fitting becomes a functioning submerged suction outlet complete with a risk of entrapment/enlargement.  Hair entanglement is the leading cause of pool entrapment – excessive velocity pulls a swimmers hair through the grate, causing it to swirl and become knotted on the other side. (WHO 2011, ASPE 2013).  Without a functioning float valve, there is no connection between the pump suction line and the equalizer wall fitting.  An open equalizer line disconnected from the pump still allows a marginal benefit from an equalization of the water level between the pool basin and skimmer, allowing the water level to drop just a small distance below the skimmer mouth before cavitation becomes an issue.equalizer01

It is becoming more common to see equalizer ports on the skimmer tied into the floor main drains which eliminates having additional submerged suction fittings.

When anti-entrapment first started gaining momentum as an issue, many manufacturers were quick to design and manufacture approved retro-fit suction covers which have no doubt lead to selling a lot more replacement pool fittings.  Retro fit equalizer covers are a little more recent on the market and there several to choose from, if you want to look at your options just call our office and let us know what kind of skimmer you have along with a picture of the existing equalizer wall fitting and/or cover that is currently installed.

One option to deal with compliance is to disable the line – as per the 2014 AB Pool Standards.  Technically you could argue the equalizer line is considered disabled if there is no functioning float valve present – without the float valve there can be no suction connection and therefore the equalizer line is no longer a submerged suction fitting.  The open line between the pool and skimmer allows chlorinated water in and out to prevent unwanted bacterial growth from occurring.  You will want to discuss this option with your health inspector as it may not be considered ‘permanently’ disabled.

The best option is to keep your float valve and equalizer line in place as it was originally designed to prevent pump cavitation.  More pools these days rely on automatic water level control systems to ensure the pool has enough water to function.  Should your level controller fail, the water level can drop below the skimmer opening after a couple days of heavy use.  Approved retro-fit equalizer covers are readily available to adapt to most configurations.

If for some reason there is no available retro-fit option you may have to consider plugging off the equalizer line.  For this to be done correctly, the pool water level needs to be lowered so the line can be completely drained and dried out.  A plug is required on both ends otherwise the end of the line will become a dead spot and an area of potential bacterial growth that can eventually contaminate the rest of the pool, we do recommend against this as some types of skimmers are more sensitive to the water level and symptoms of cavitation can be experienced from the turbulence of splashing at water levels that are just slightly below normal operating.

Just like with main drains on the pool floor, anti-entrapment compliance for equalizer lines is an ongoing responsibility.  The risk is not totally mitigated once approved covers are installed.  We strongly recommend that the designated operator communicate to all involved staff about the importance ongoing anti-entrapment assessment.  We all know how important it is to test the water before allowing bathers to use the pool, a good practice for safety and risk management is to also ensure your submerged suction fittings are present and in good working condition.  While entrapment & entanglement incidents are rare, most accidents are due to missing or damaged covers.equalizer adapt


  1. World Health Organization (2006) Guidelines for safe recreational water environments. Vol. 2. SWIMMING POOLS AND SIMILAR ENVIRONMENTS. Geneva, World Health Organization.
  2. American Society of Plumbing Engineers CEU 202 – Public Swimming Pools. August 2013

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