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Understanding the Winter Blow-out Process

What happens underground in the winterizing process?  By setting up a clear PVC pipe system we can visualize the process and some of the challenges to winterizing pipes.   This demonstration shows us that effectively utilizing the proper equipment and  technique for blowing out plumbing lines is crucial for consistent, successful winterization. It is important to understand the three main phases of the process:

    • Water purge phase
    • Line clear phase
    • Sealing/securing phase

In the water purge phase, the water that fills the lines is “pushed” out of the pipe and replaced with air.  Several factors are important to accomplish this part of the process effectively.  First of all, the air source you use must provide enough air pressure to counter the back pressure of the water in the pool.  When blowing out return lines this is a pretty low threshold, however when purging water from the main drain line a minimum of 4 psi of pressure must be achieved to push against the 8 feet of water in many deep ends.  The second important factor during the purge phase is the amount of water flow that can be pushed through your blow-out plugs.  The wider these plugs open under the appropriate pressure the more water you will be able to clear from the line at a fast rate.

The line clearing phase happens after most of the water has been purged from the lines but may still remain in low parts of the plumbing.  Your ability to generate a high air flow rate through the purged lines is the critical factor in successfully blowing this remaining water from these locations.  Choose an air source that delivers at least 100 cubic feet per minute (cfm) of air flow – most compressors only produce 2-5 cfm so you will need a blower.  And again, use blow-out plugs that open wide at low back pressure to assure that the blower’s power can be realized as flow through the pipes.  On return lines with more than one return branching off the main line, strong air flow to the farthest branch can be achieved by blocking the flow of cleared branches earlier in the run.

Once the lines have been cleared of water they must remain so over the course of the winter, so the plugs must effectively seal to prevent water from re-entering the plumbing from the pool.  It’s still a good idea to pour antifreeze into the cleared lines just in case undiscovered cracked fittings, damaged threads, or badly installed plugs allow some water back in.   After pouring antifreeze into the cleared line, turn the blower back on just long enough to see it blown into the pool through your blow-out plugs.  The remaining anti-freeze will settle into low spots in the plumbing  . . . just the spots that would be prone to problems if water got in.

Anderson’s Big Blue Blower and Winter Duck Plugs deliver the performance you need to assure each phase of the blow-out process is done effectively.  The blower produces enough pressure “umph” to blow-out even the deepest main drain and provides an exceptional amount of air flow to clear all low spots in plumbing.  Winter Duck Plugs open wide at low back pressures to clear lines quickly during the water purge phase and enable high air flow during the line clearing phase.  Additionally, they can be easily blocked during this clearing phase with simple office binder clips to facilitate flow to all branches of the return system.  Most importantly, over the past 10+ years, Winter Duck Plugs have proven themselves dependable at keeping water out of lines and protecting thousands of pools from winter freeze damage.

For a comparison of how  Winter Duck Plugs compare to other blow-out plugs on the market see the results of our testing here.

How to Gather Good Information for Efficient Leak Jobs

An efficient leak detection job starts well before you open the gate to your customer’s back yard.  You can save a great deal of time by gathering and processing information about the suspected leak before the job is even scheduled. Make a practice of purposefully communicating with the pool owner to accomplish the following 3 objectives as the first part of your leak detection process.


1. Make sure there really is a leak

Sometimes customers are concerned about water loss that may be the result of something besides a leak.  Evaporation, splash-out, or even miscommunications about when a backwash was performed can result in panicked calls to a leak professional.  It’s hard to charge for a leak job if there isn’t really a problem (even after you’ve spent a lot of time looking for the non-existent leak), so it’s important to ask enough questions upfront to eliminate the possibility that the symptom they describe is anything but a leak. It’s also a good idea to schedule jobs far enough out to give the customer time to do a Bucket Test for themselves to confirm the water loss they are observing is not just due to evaporation.

Example Questions to Ask:
  • Why do you think you have a leak?
  • When did the problem start?
  • How much loss are you experiencing per day?
  • When is the last time you backwashed the pool?


 2. Collect key facts that allow you to start processing the problem before you get to the pool

Leak detection is as much mental as it is physical .  Your observations and tests at the pool are just one source of clues that can lead you to solving the elusive problem.  By asking strategic questions of the pool owner before you get to the job, you can start thinking about and solving the problem even while you are driving. Knowing when the pool was built, who built it, how it is used, and when it started leaking can provide clues to where the leak will be, especially as you start building a mental database of previous leaks you’ve found.  Other information about the nature of the problem, like whether it leaks more with the pump on or off, will also help to establish what part of the pool may be the most suspect.

Example Questions to Ask:
  • How far down have you let the water level go?
  • Does the pool have any unique features such as an attached spa, waterfall, or in-floor cleaning system?
  • When was the pool built and who built it?
  • Who typically uses the pool and how do they use it?
  • Have there been any unusual events associated with the pool recently?
  • Have you recently had repairs or construction work done in or around the pool?


3. Clearly establish what the expectations are for the condition of, and access to the pool

Generally the tests you do on site will require that the pool be filled to its normal operating level. Make sure the customer knows this.  You may also have to get in the pool for inspection and repair, so it’s a good idea to request the pool be clean and warm if possible.  Of course, you can’t work on a pool that you can’t get to, so make sure the customer provides information on how to access the pool in case they aren’t there.  It’s easy to assume that these simple and common sense issues will be obvious, but a few wasted trips to a pool reinforce the fact that it’s better to err on the side of over-communication.

Example Questions to Ask:
  • Is the pool filled to its normal level?
  • Do I need any keys or codes to access the pool and equipment?
  • Is the pool clean?
  • Will you be home when I’m working on the pool? If not, how can I reach you during that time?


For more in depth discussion of the information gathering step and how it fits into the rest of the leak detection process check out the slide shows available in our resource center.

Pressure Testing Myths Busted

Pressure testing is a topic where a number of myths and misunderstandings have developed in the swimming pool industry. Below, we explain the truth behind 4 common misconceptions that should help you stay focused on efforts that will lead to leak detection success and profits.

MYTH #1: Pressure Testing is Unnecessary for Leak Detection

While you may be able to find common leaks without pressure testing, if you want to leave the pool assured that you have found all of the leaks . . . and you want to give the customer that assurance, pressure testing is critical.

There are other ways of finding easy to reach leaks in plumbing, but from the standpoint of conclusively determining if the entire line is leak free, nothing beats a properly performed pressure test.  Furthermore, despite advancements in cameras and other probes that have applications in some situations, the most common and dependable way of pinpointing leaks underground involves the use of a listening device that picks up the sound of pressurized air escaping from a leak into water saturated soil.

MYTH #2:  Air Can Be Used Interchangeably With Water for Pressure Testing

Air and water behave very differently in pressure testing situations.  Understanding three pressure testing principles that address these differences is important as you determine when to use air and when to use water to build pressure.

  1. Air compresses under pressure, water does not
  2. Air stays at the top of the pipe, water stays at the bottom
  3. Air escapes from leaks faster than water does

Our pressure testing slide show provides helpful diagrams and more explanation of how these principles affect your test results.  As a general rule it is best to use water when testing to determine if the line is leaking since it does not compress under pressure so it will show a loss in pressure quickly, even with a small loss in volume.  On the other hand, air trapped in a line can expand as water volume is lost from the leak, slowing (and sometimes completely masking) a drop in pressure. Additionally, if plugs happen to pop out under pressure they will come out with much less force if the line is pressurized with only water . . . trapped air will propel a popped plug like a cannon ball!

The main benefit of using air is that it makes a much better noise escaping from the pipe into water saturated soil than water does.  So, once you have identified a leaking section of plumbing with a water test, switch to air to produce a good noise that can be picked up by your listening device.

Myth #3: Air and Water Can Be “Mixed” in a Pressure Tester and Will Stay “Mixed” Inside the Pipe

We’ve debunked this myth by testing it on a plumbing system made of clear PVC.  Regardless of how they are transmitted into the pipe, water stays low and air stays high.  They do not stay mixed up just because they are put under pressure.  This is simple physics and anyone who says otherwise is selling you hocus-pocus.

Adding both air and water to a line is not the first step you should take when trying to make a good leak noise.  While it is indeed important for the soil to be full of water outside of the pipe where air will blow out through the leak, no noise is made unless air actually gets to the leak.  Since water stays at the bottom of the pipe and air at the top, if the leak is in the low end of the plumbing no air will get to it if you are adding both air and water.  So, all of the water above the leak level must be purged from the line before this happens. Generally this is best accomplished by removing a low plug and blowing air from the high end.  Once you see bubbles, replace the plug, set your air source regulator to maintain no higher than 5 psi, and begin listening.  Larger leaks and/or leaks in soil that drains quickly may necessitate adding water while air is going into the line.  To avoid noises inside the pipe, do this with a separate pressure tester from the low end of the plumbing.  The best results happen when air and water do not mix inside the plumbing . . . just at the leak!

MYTH #4: Certain Kinds of Gas Make Better Noises Than Others for Leak Location

Any gas escaping from a leak will make bubbling/gurgling /hissing/spotting sounds in the full range of sonic frequencies that can be picked up with a listening device.  Sometimes, leak detectors will use nitrogen tanks to deliver the gas into the line quietly (without the conflicting sound of a compressor).  However, these tanks are used not because of any special characteristic of the gas (in fact, the air we breathe is made up of 78% nitrogen) but because of its ease of availability and inexpensiveness in relation to other gasses.  SCUBA tanks adapted with an adjustable regulator can also be used if you can get them filled.  A small compressor works just fine for inducing air pressure, especially if you use a 50 foot hose that allows you  to position the compressor some distance from where you are listening.

In some situations where soil or leak conditions make it difficult to create a noise helium gas is used to find underground plumbing leaks.  In these situations a Helium Detector picks up the presence of the gas as it makes its way to the soil’s surface.  Helium is not being used because it makes a better noise, but because it can be detected by this detector.

If you have any questions about pressure testing or swimming pool leak detection, consult the Resource Center of our website or give us a call.

Pipe Inspection Camera Use and Selection

Pipe Inspection Cameras for Swimming Pool Use

The digitalization and resulting miniaturization of cameras over the past years has led to a proliferation of inspection cameras for all types of uses.  There is great benefit to being able to “get into” and see areas that have previously been inaccessible. Pipe inspection has been a major area of application and product development for this technology.

Naturally, because of the prevalence of underground plumbing, there is great interest and intrigue in applying this technology to the swimming pool industry.  Indeed, an inspection camera may prove to be an important part of your equipment arsenal for finding leaks and other related problems.   As you consider an investment in the wide range of options available, it’s important to consider the unique characteristics of pool plumbing and the types of problems you’re looking for, as well as establish a clear expectation of the real benefit and usefulness they will provide to your business.

One Length Does Not Fit All

Many leak problems can be identified within the first several feet on an access point. In these situations, affordable fiber optic technology can be applied to the problem.  The Rigid Inspection Scope comes with a 3 foot flexible extension that allows you to get into easy to access small openings.  Range can be extended with optional 3 foot extension (providing up to 6 feet of reach).  Inspection Scopes are great for looking inside return fittings, skimmer throats, and light niches without having to get into the pool.  Extension tubing for dye testers can be taped to the side of the extension with the tip extending in front of the camera in order to dye test in these hard to reach spots.

If you want to go further than the first several feet into a pipe you will have to add a Camera/Push Rod system to the Inspection Scope.  These robust systems have become a staple item in the plumbing, sewer, and municipal industries.  Their use on swimming pool plumbing, however, offers certain challenges.

Pool Plumbing: A World of Small Pipes and Lots of Corners

The first thing to consider about pool plumbing is that relatively speaking (at least in terms of where most pipe inspection cameras are used),  it is on the very smallest end of range most cameras can be used on. Pushing a camera into this small pipe, especially around elbows and T’s presents problems.  Bruce Roache of CT says that in 1 1/2″ plumbing his Rigid Micro Camera is “great on straight runs and can reliably get through the first 90 degree bend, but it has been so difficult to get past a second 90 degree corner that I don’t do it anymore for fear of getting it stuck or damaging it as I pull it out.”  Christine Pearson of Excaliber Leak Detection in MD uses her Rigid Nano extensively and can get it through more than one elbow.  But she admits that even this device can be damaged when pushed too far.  “If you are hoping a pipe camera will enable you to quickly inspect an entire plumbing system you will be disappointed. A camera won’t replace other methods of detecting and locating leaks in the plumbing.  But, if you want clear evidence of problems in the areas it can reach, the images and video it provides can’t be beat.”  Actually being able to see things like big leaks, obstructions in the line, and crushed pipe can help determine the cause and repairability of the problem, and communicate clearly with the customer.

Bubbles are clearly visible from this suction side leak while the pump is running.

While small PVC pipes with elbows and T’s can pose problems, straight runs and flex-pipe are prime applications for a Camera/Push rod system.  “It is awesome in flex-pipe,” says Roache.  “Although I think flex-pipe is terrible, it is very common in my area.  Nothing is more convincing to a customer, pool builder, or building inspector than a live video image of the leak, the problem, or the building code pass/ fail issue!”

“We use it extensively on flex-pipe,” says Christine.  “It’s especially useful on skimmer lines where we can show evidence of the damage chlorine tablets in the skimmer basket produce, or even see bubbles being pulled through a leak while the pump is on.”

Chlorine damage on flex pipe

You Found the Leak, Now Where is the Camera?

Once a problem has been found with a camera, determining its location on the deck so a repair can be made is the next step.  Depending on how far in you’ve pushed the camera, and your knowledge of where the lines run, you may be able to estimate the location.  Otherwise, you’re going to need to invest in one more piece of equipment.  A line locator detects a radio frequency signal emitted by a transmitter built into the camera head.  The line locator will enable you to determine location, direction of run, and depth of the pipe.  These devices can also detect signals in conductive pipes, tracer wires, electrical lines, or battery operated transmitters that aren’t incorporated with the cameras.  For many pool leak specialists, adding a camera and line locator to their tool arsenal has been the catalyst to expanding their business into other lucrative location/inspection markets.

A Note on Purchasing Equipment

Once you have decided whether an inspection camera and scope system is a worthwhile investment, there are a lot of options out there for purchasing .  A quick search on the internet will reveal a multitude of devices at all levels of sophistication, quality and country of manufacture.  Because swimming pool use can be hard on cameras (pushing and pulling them through sharp 90’s) don’t compromise on quality.  We distribute Ridgid products because we feel most comfortable with their experience and knowledge of the swimming pool industry.  Ridgid has also proven to be responsive when repairs are needed.  Please feel free to contact us if you have any questions.

What makes a top notch listening device?

When it comes those tough underground plumbing leaks, electronic listening devices are the backbone of the leak detection industry.   While there are other methods the most reliable and consistent method is to make a noise at the leak with pressurized air escaping into water saturated soil, then listen for where the noise is coming from.  This noise can sometimes be picked up by just an open ear but often a listening device is needed to help amplify the sound and filter out other noises to focus in on leak sound and pinpoint location.

Choosing the right listening device for your company is an important decision. When researching a product purchase, similar to listening for a leak, there can be a lot of “noise” to sift through.  Here at Anderson Manufacturing we have combined research and testing with the experience of hundreds of pool leak detection professionals to find and keep the best option for a swimming pool leak listening device.

While there are many factors to think about such as cost, dependability and service after the sale. There are also some more technical criteria to consider when looking at purchasing a swimming pool leak listening device.   Since listening devices range from your standard geophones to sophisticated technology here are some tips for what criteria to look at.

Important criteria to consider when comparing listening devices:

Sensitivity – how well the device amplifies sounds from the transmitting material 

Frequency Range – how broadly the device can hear all the sounds created by a leak

Filtering – how effectively the device can filter out background noise enabling  you to focus on a leak sound

The Bigfoot microphone for the XLT30H reduces outside noise interference.
The Bigfoot microphone for the XLT30H reduces outside noise interference.

The standard ground microphones that come with Fisher’s XLT17 and the XLT30H listening devices, use piezoelectric microphones because these are known to be the best type of microphone to use in situations where sounds are being picked up from liquids or solids.  Virtually every company that makes serious equipment for locating underground plumbing leaks for municipal work incorporates piezoelectric technology. Accessing the technological knowledge of those who have experience in this area is one reason we have chosen to work with Fisher and utilize their products.  This type of equipment requires more specialized expertise than standard microphone amplification (that used for music/voice etc.).

In practice you will find that sensitivity by itself however is not the only important performance criteria.  Most any device will be able to amplify a sound to the point that it will hurt your ears.  What’s more important is hearing the right sound and distinguishing it from background noise.  That’s where the other two important criteria come into play.


Frequency Range

Both pressurized underground plumbing leaks and static shell leaks in the pool make noises in a wide range of frequencies depending on a variety of conditions.   We like to think of the sounds a leak makes in the same way we do instruments in an orchestra.  You want to be able to hear everything from the shrillest piccolo to the deepest tuba.  Although every leak is different, as general rule underground plumbing leaks make sounds in the lower frequency ranges while static leaks in the shell of the pool are in the higher range.  If your listening device doesn’t pick up sounds at the top or bottom of this range you will be missing the fullness of the sound a leak makes or you may miss it altogether.  Both the Fisher XLT17 and XLT30H pick up sounds in a frequency range of 20Hz to 6000Hz.  In addition, the XLT30H includes a switch that enables the unit to work effectively both when sounds are in the low range (for underground leaks picked up by the Bigfoot microphone) and the higher ranges (for underwater leaks picked up by the hydrophone).


Filtering Capability

The final performance criteria, and what we consider to be the most important for swimming pool applications, is an area where Fisher devices particularly shine over all others we have researched.  A listening devices filter allows you to specifically highlight (or eliminate) a specific range of sounds.  Consider for instance that we only wanted to hear the violins in the orchestra of leak sounds we imagined above.  Filtering is important because the devices are so sensitive that we will likely hear other sounds around the pool (it always seems as though the next door neighbor want to mow their grass when you’re trying to find a leak!).  The filter helps us zero in on the leak sound without being distracted by the background noise.  Additionally, different ranges of sound behave differently underground or underwater.  Low frequency sounds travel much further than high frequency sounds.  By selecting high frequency sounds once a leak sound has been identified the frequency filter can help in pinpointing leaks to a small area.


Fisher devices provide a wide range of filtering options to address most any scenario. The Band Pass filter allows selection of a narrow band of frequency anywhere in the range of sound.  The Hi Pass filter focuses high frequency sounds providing adjustment of the low end of this range.  The Low Pass filter does the opposite – focusing on the low end and providing an adjustable high end..  The XLT30H also includes a Notch Filter that allows the elimination of a specific frequency range (for instance to minimize the “hum” of a nearby air-conditioner) and can be used at the same time as the other filters.


Another noise minimizing feature available on Fisher devices is especially important when the unit is used for listening to pipes in the ground.  The Bigfoot muffler utilized by Fisher to minimize outside noises transmitted through the air is the best we’ve seen.  This rubber boot deadens outside noises preventing them from reaching the sensitive piezoelectric microphone which makes direct contact with the pool deck or ground through a heavy aluminum foot.



Ultimately, we are convinced, that Fisher Listening Devices as sold by Anderson Manufacturing Co. are the most technologically advanced, well rounded tool for all types of swimming pool acoustical leak location   They have been continually improved through the years and currently represent the best package for addressing pool leak problems in both the plumbing and shell.  We back our belief with the evidence of thousands of successful customers and a satisfaction guarantee that promises your money back if you are not satisfied with their performance.

If you have made it this far through this you have taken in a lot of information, hopefully it has been helpful in making decisions that will affect your leak detection success.  Remember you can always call and talk through the buying process or for technical help regarding a leak or leak detection equipment. Thanks for reading!


Pressure Testing: Putting The Pressure On

Regardless of whether the leak is suspected to be in the plumbing or the structure of the pool, a pressure test should be done to provide confirmation of which parts of the pool are leaking, and which can be eliminated as suspected leak areas. This is important not only because it saves time in later leak location steps, but also because it allows the technician to provide the pool owner with the assurance that leaks have been found and fixed are isolated to the pool.

To do a pressure test, closed test plugs are used to block off all but one of the exposed openings of a section of plumbing. A pressure induction system is put in the remaining opening (usually at the equipment). Water is then induced into the line through the Pressure Tester and the system is brought up to no higher than 20 PSI. A pressure drop indicates a leak. A line that holds pressure can be eliminated as a potential leak area.

(Above is a video on how to pressure test)

While a pressure test of an entire plumbing system may be adequate in situations where a structural leak is suspected, individual sections of plumbing should be tested if a plumbing leak is suspected. Valves at the equipment can often be used to isolate these sections as they are tested first. Do so by testing from the equipment to the closed valves to see if they hold pressure (illustrated below).

OPEN PLUG in pump
Pressure test from pump for isolating suction side plumbing.

Water is used for this isolation pressure test because it does not compress under pressure and as a result gives more accurate and quick results. Water is also advantageous for this test because if test pressures get higher that a safe level, plugs that pop out under water pressure will not fly from the openings as a dangerously as those that pop out under air pressure.

Accept no compromises when it comes to the sealing effectiveness of your test plugs. Tapered plugs have tendency to pop out under test pressures wasting valuable time and putting anybody in the area of the tapered plug at risk of injury. Plugs with straight-sided rubber and large corrosive resistant hardware allow for extra sealing area, easy expansion, and ultimately more accurate results.

Your pressure induction system should allow for easy access to a variety of different plumbing openings and allow the introduction of either water or air (for later leak location steps) into the plumbing. A system utilizing various sizes of open stem plugs, which can be quick-connected to the pressure tester, provides the ability to do this without having to cut lines or jerry-rig fittings. A pressure tester should include a 0-30 PSI gauge, hook ups for a garden hose and air line, a valve to control these and block off the system, as well as a means of releasing pressure from a line that has been tested but does not leak.

For additional information and a comprehensive step by step slideshow on pressure testing click below:

plumbing line leaks

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