Pool Liner Damage

What are the black stains on the floor of my liner and how do I get rid of them?

If you have black or grey cloud-like stains on the floor of your in-ground vinyl liner, they are most likely caused by bacteria that is living in the ground under your pool.  Bacteria sometimes show up years after a pool has been installed.  We think the bacteria can be washed into your pool area by flooding rains or when a septic tank overflows.

There is little proven research on this topic but we understand the bacteria actually gets sunlight through the water, eats on some food source in the ground and then secretes a dye-like material that migrates through the vinyl and shows up as a stain on the floor of your pool. Often these spots appear grey, greyish green or light black in color. Once the spots appear, the damage to your liner is done and it’s irreversible.  Algaecides and other chemicals used in the pool will have no effect on these stains since they can’t get to the source of the problem which is the bacteria in the soil.

So you live with stains as long as you can and then, when it’s time to change your liner, it’s also time to try and get rid of the bacteria to avoid a repeat problem with staining. No one knows precisely how to solve this problem but there are four methods that we understand may be effective.  You may want to choose one or even try all four.

  1. The simplest way to attempt to kill the bacteria is to have your contractor spray the floor of the pool with liquid chlorine before installing your new liner. Chlorine bleach works fine and they will mist the floor of the pool using a garden sprayer three or four times.
  2. A second possible solution is to change the pH of the soil under and around the pool.  This is done with a chemical called Copperas Iron Sulfate (FeSO4) which is available at tree nurseries or agricultural supply houses. The chemical is sprinkled on the ground around the pool and on the floor of the pool and then the ground is saturated with water for two to three days. The idea is to get the powder deep into the ground so it can change the pH of the soil and kill the source of the bacteria.
  3.  Since bacteria need sunlight to grow, a third option is to eliminate the light source by putting a black sheet of plastic under the liner. This is not advisable if your yard has a high water table as rising water may float the liner and ball up the plastic underneath causing an even bigger problem than the stain.
  4. Finally, some companies are selling a roll-on epoxy-like stain barrier paint to cover the floor and walls of your pool.  It’s like a liquid plastic that sets up hard to form a membrane intended to block out the light and prevent stains from getting to your liner. It is the most expensive of the options but some people claim it really works.

Discuss these options with your local pool professional and depend on them to suggest which method they have tried and found to be most effective.

Moldy Pool

Is it ok to put chlorine tablets in my skimmer instead of using a chlorine feeder?

The answer is yes, many people do just that, but you can get in trouble if you don’t run your pump runs 24 hours a day.  We would not recommend putting tablets in your skimmer if you operate your pool on a timer and you can also get in trouble if the power goes off.

The chlorine tablets are concentrated and they have a very low ph.  When your pump is running, the water going through your skimmer is constantly eroding the tablet, adding chlorine to the water which quickly makes its way through your filter system and into your pool.

If the pump goes off, now that tablet is sitting in just a few gallons of water and the chlorine level rises and ph drops. Now you have a skimmer full of highly chlorinated/acidic water and when it sloshes out of the skimmer and back into the pool with the regular movement of the water in your pool, that caustic water runs right down the face of the wall and can burn your liner as shown in the photos below.  This will damage and permanently discolor your liner.

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How can I prevent my pool liner from having discoloration, deterioration and “dry rot” above the water line?

We recently had a homeowner ask a question in response to our blog post, What are the causes of discoloration, deterioration and “dry rot” above the water line on a pool liner?

My pool is doing all three of these and it is only six years old. How can I prevent this from happening again?

As our blog article states:

There are three main contributors to this problem: chemical attack, high temperatures and UV rays.  However, the UV resistant characteristics of pool vinyl are excellent and the UV rays themselves do not present a significant problem.

Clean your pool often by taking a soft cloth and rinse the contaminates from the vinyl using the pool water.  Substances such as body oil, sun tan lotion, baby oil, etc., will collect at the water line.  These substances, when exposed to the sun and the high temperate that can be found just above the water lines, will oftentimes turn brown and can be very difficult to remove from the vinyl.

We should have added that chemical attack means high chlorine and/or a low ph.  The two things you can do here are to not over chlorinate and to keep your ph at 7.2 or higher.  These are the two most critical things you can do to prevent dry rot.

The other issue is high temperatures.  Your pool vinyl is not intended for use over 80 degrees.  On the hottest summer days, you can direct your return nozzles up so that the water shoots up out of the pool.  This will cool the water overnight.  If you have a heater, don’t set it too high.

I would also add that covering your pool during the off season can significantly increase the life of the liner since it’s out of the sun and without chlorine for much of the year.  I think this is why liners always last longer in NY than they do in Texas.

I would also add that this homeowner’s liner made it six years and the average life is seven.  It failed a little earlier than expected, but not by that much.

Hope this helps!

What would cause the pattern to flake off or rub off a vinyl pool liner?

To answer this question properly there must be a basic understanding of the procedures involved in the printing of your pool liner. The print pattern is applied by a process called “roto-gravure” printing. The inks used are solvent based and when applied to the vinyl, they actually bond themself to the vinyl by “biting” into the vinyl. Then a clear “top coat” is applied to increase abrasion resistance and provide an added layer of UV protection.

The cause of ink flaking off the vinyl is low water PH. An acidic environment will weaken the bond by softening the coating, and eventually the ink. The more acidic the environment, the greater the likelihood of damage. The effect is cumulative and irreversible. Once this softening occurs, the coating and ink are susceptible to abrasion and flaking.

Always keep your pool at the recommended PH of 7.4 to 7.8. Deviation from these levels will adversely affect the performance of your liner.

*The information provided comes from one of our liner manufacturers.

What is the cause or causes of color fading below the water line on a pool liner?

There can be many contributing factors that lead to the fading of your liner.  All of those factors can be grouped under the heading of chemical attack, however the leading cause is simply over chlorinating.  Just as excessive use of bleach will fade your clothes, over chlorinating of your pool water will greatly accelerate the fading of your liner.

From the vinyl’s standpoint, any chlorine level above 3 PPM will accelerate the fading process.  The use of a chlorine based sanitizing system is going to bleach your liner, there is no way around that.  The higher the active chlorine level, the quicker the fading will occur.  Be especially careful when shocking, closing or opening the pool.  It is critical that you circulate the water for a minimum of 72 hours after any of these procedures.  The average shock treatment is going to bring the chlorine level of your water to at least 25 PPM and as high as 50 PPM.  The specific gravity of the chlorine is higher (weighs more) than that of the water.  It is therefore critical that you circulate your water long enough to insure that the chlorine will not settle out of the water and concentrate in the deepest part of the pool.  It is also important that you do not cover your pool for at least 24 hours after one of these treatments.  The covering of the pool will greatly restrict the chlorine’s ability to dissipate, thereby greatly increasing the likelihood of damage.

Our experience has shown that of all the sanitizing systems, Trichloroisocyanuric acid has the greatest potential to bleach a vinyl liner.  Alkaline sanitizers (Hydochlorite) are much more vinyl friendly and just as effective.  No matter what system you use, always use the minimum amount of chemical that will get the job done.

Remember: Less is best when adding chemicals to your vinyl lined pool.

*The information provided comes from one of our liner manufacturers.

What are the causes of discoloration, deterioration and “dry rot” above the water line on a pool liner?

In most cases, these three problems are different stages of the same phenomenon.  The causes of these problems are many and varied, but have a universal theme.  In most cases, the discoloration (usually brown), the deterioration (stiffening of the vinyl) and then the complete failure of the vinyl, commonly referred to as “dry rotting,” is due to the extraction of the plasticizers and stabilizers from the vinyl.  (Plasticizer is the additive which gives the vinyl its flexibility; stabilizers give the vinyl its high temperature stability.)  Under normal circumstances, the volatility of these additives is very low and the vinyl will maintain its physical characteristics for many years.

Experience has taught us that under certain circumstances the area above the water line can begin to deteriorate very quickly.  There are three main contributors to this problem: chemical attack, high temperatures and UV rays.  However, the UV resistant characteristics of pool vinyl are excellent and the UV rays themselves do not present a significant problem.

Clean your pool often by taking a soft cloth and rinse the contaminates from the vinyl using the pool water.  Substances such as body oil, sun tan lotion, baby oil, etc., will collect at the water line.  These substances, when exposed to the sun and the high temperate that can be found just above the water lines, will oftentimes turn brown and can be very difficult to remove from the vinyl.

* The information provided comes from a vinyl manufacturer.

Can ants or termites attack a vinyl pool liner?

When an inground pool with a liner is leaking, there are only about five things that can be wrong:

1. Your liner may have a split seam.

2. There may be a hole poked or ripped in your liner.

3. There may be a leak in your pipes.

4. There may be a leak in the face plates of the steps, skimmers or return fittings.

5. Your liner may have been attacked by ants or termites.

In trying to find and correct the source of your leak, it’s helpful to look for the most common possibilities first and then to eliminate these possible problems one at a time.  I will try to address each of these problems with a different post over the next few months.  Let’s begin today with the least common of the potential problems: ants or termites attacking your liner.  I have only seen this happen a few times in 30 years.  It makes sense that these bugs, thirsty for water, come up through the ground and chew their way through the liner, causing leaks.  These attacks seem to happen more in arid regions, regions with lots of termite activity, or in periods of drought when insects are desperate for moisture.

I am told that if you look from the backside of the liner, you can actually see the “teeth marks” in the vinyl.  I am also told that you can see the “trails” they leave in the sand or vermiculite floors, much like you would see in an ant farm toy.

-Robert

* The following article was written by a liner manufacturer:

TERMITES AND ANTS

For many years, it has been known and proven that termites and ants will attack a vinyl pool liner.  It is suspected that the termites are attracted to the pool area due to the dampness around the pool.

Usually, the first signs are very small holes in the liner in the area above the water line.  Quite often, the liner may have dozens of holes in it within a short period of time after they have begun their attack on the liner.

Most of the time, if the liner is taken out of the bead track and pulled away from the wall, you may see the trails that the termites have left behind.  Usually the holes they make in the liner are relatively small, about an eighth of an inch in diameter and are round or oval shaped.

If the pool liner has to be replaced as a result of termites or ants, the homeowner is advised to get an exterminator to treat the ground beneath the liner and around the perimeter of the pool deck.

Here are some of the more likely places for termites and ants to appear:

  • A yard where a tree has been removed
  • A yard where a patio or walkway has been removed
  • Around wooden flower planters
  • Around wooden fences

Although this is not a widespread problem, it should be taken seriously.  An average of ten to fifteen cases a year are reported to us.

Liner wrinkles from rain water

It has rained all season long, your backyard oasis has turned into a pile of mush, and the rain has caused the one thing pool owners don’t want to see – liner wrinkles.

There are two issues here:  how to get rid of the wrinkles, and how to keep this from happening again.

Wrinkles can be caused by ground water, but if the liner looks “pruned,” the wrinkles are most likely due to water absorption. The debate is why did the vinyl absorb water? Is it improper chemical balance or is the material in your particular liner less resistant to absorption than it should be? With a pruned liner, you should always make a warranty claim and see if the manufacturer knows of a any material issue around the time your liner was made, We will talk more about water absorption in another post…

photoDuring periods of heavy rain, if the water level in the ground becomes higher than the water level in the pool, the liner will float.  When the ground water recedes, the liner comes back down.  If there is no vacuum on, the liner will stretch back into place unevenly, creating wrinkles in some areas and a tight stretch in others.  Usually the wrinkles are in the shallow end.

The solution is to drain the water about one foot back down the slope to the deep end, below the floor in the shallow end.  Pull the material back up into place in the shallow end, turn on a vacuum blower (just like during the initial installation) and refill the pool.

There are all kinds of ways to get in trouble here, so this is definitely a job for your pool professional.  If the ground is still saturated with water, the pool walls may collapse under the extra weight.  You may need to wait for drier conditions before attempting to re-seat the liner.  If the liner is more than a few years old, it may be brittle and may rip when you try to get it back in place.  The liner could also tear away from the face plates around the steps and skimmers.

The bottom line:  It is probably a simple and inexpensive fix.  Your contractor just drains some water, re-seats the liner and fills it back up.  Be aware that the liner may fail during the process, but if the liner is more than seven years old, it is about time to replace it anyway.

The second question is how to keep the liner from floating again when you have the next big rain.  You may need to install drains to carry water away from the pool area, or you may want to install a well point and pump to take care of the underground water.  Or you may just decide that this is a once every 10 year event that you can live with.

We have provided several pictures of liners that floated as a result of excess rain water.  You can see the liner wrinkles caused by the floating.

06-14-pool-liner-bubble-004

floating liner 1

 floating liner 2

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