What are the effects of salt water chlorine generation systems on vinyl pool liners and swimming pools?

What are the effects of salt water chlorine generation systems on vinyl pool liners and swimming pools?

The growing use of pool chlorination by salt water chlorine generation systems has added some serious implications for pool liners, steel walls and equipment that need to be considered.

Let’s start by making the following statement:  Salt water in the swimming pool, maintained at the recommended concentration and PH, does not constitute any potential for either equipment corrosion or liner deterioration.

However several other important factors need to be considered:

  1. The splash out areas around the pool, where deck, coping and equipment are wetted by salt water, will go through a cycle of wetting and drying, creating much higher concentrations of salt and salt residue, which is much more corrosive and will etch decking and corrode exposed aluminum and metal fittings and deck anchors.  It is recommended that after each use, the areas are flushed with non-saline water.
  2. High levels of chlorine will damage liners and equipment much the same way as high salt concentrations would speed up the corrosion of metal components.  Because chlorine is continually generated in a salt system, unless monitored, it is very easy to have chlorine concentrations well above the recommended levels which will have adverse effects on pool liners.
  3. The prolonged use of solar covers will allow the chlorine levels to build up to higher than normal levels as the chlorine cannot dissipate or gas off into the air.
  4. Auto-covers kept closed for long periods of time create the same build up of chlorine which can damage the cover and the uncoated aluminum components.  This can be more drastic because the condensation that will occur under the cover will coat all areas under the cover and lead to a buildup of salt levels as well.
  5. The continual generation of chlorine does not have the same build up of chlorine amines as normal chlorination.  The chlorine amine is what provides the characteristic chlorine smell and consequently, in salt pools this lack of chlorine smell may lead users to assume the chlorine levels are at an acceptable level and not monitor the water chemistry as often as necessary.
  6. Salt Systems are often sold as low maintenance products and the users are not educated properly.  The assumption that these systems require less maintenance applies only to the addition of chemicals.  The water testing and monitoring frequency is the same as for conventional pools and perhaps for many of the reasons mentioned above, even more attention is required as high concentrations of chlorine over even short time duration can and will alter the vinyl and affect other metal pool components.  High chlorine concentrations can also cause a swing with the levels of other stable water components such as PH and total alkalinity.  Both are instrumental in balanced water which is critical for the longevity of pool liners and components.

*The information provided comes from a pool manufacturer.

I have a stain on my vinyl liner. How can I tell if it is from algae or minerals?

This is a tough question. Below is a suggestion from one of the product engineers at the plant that makes the actual vinyl sheet.

The following approach could be used to narrow down the possibilities; however, there is risk of damage to the print pattern and liner material in doing so.

First, try direct contact on a small spot with some pH down in a sock to see if there is any change in the stain. If there is no change, the same approach can be tried with a neutral or high pH sanitizer (i.e. dichlor or calcium hypochorite).

If the pH treatment alone reduces the stain, it is likely a mineral stain. If the chlorine application reduces the stain, it is a microbiological stain, such as an algae.

If the stain is from algae growth on the back side of the liner, any success on removing the stain will likely only be temporary.

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 best time of year to replace my inground vinyl pool liner?

Pool owners in need of a replacement liner often wonder when the best time is to replace and install their new pool liner.

If you choose to replace your liner in the spring, the key is to pick your day carefully.  It has to be warm outside, but the sun also has to be shining.  It is the sun beating down on the vinyl on a warm day that loosens it up and allows the material to vacuum into place properly.

We used to suggest installing liners on a day no cooler than 60 degrees and sunny for 20 mil liners.  Today, we suggest 70 degrees and sunny for 27 mil liners.

If you choose to change your liner in the fall, your pool will be ready to go on the first day of spring.  This prevents any waiting in the spring to get on anyone else’s schedule or for the weather to break.

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.

Should I use a floating chlorine dispenser in my inground liner pool?

We do not recommend using floating chlorine dispensers in inground liner pools.  They are great until they get caught in the step or skimmer area or sink to the floor of the pool, laying chlorine right onto the vinyl.

Below, you can see the chlorine damage to a vinyl liner caused by a floating chlorine dispenser.

floating chlorine dispenser damage

 

 

 

 

 

 

 

 

 

 

 

floating chlorine dispenser damage 2To the left is another example of chlorine damage from a floating chlorine dispenser.  The floating chlorinator got caught under the solar cover against the wall and bleached the liner.

We recommend always introducing chlorine into the water though the skimmer or automatic feeder.  Be careful with your vinyl and don’t ever put chemicals directly in the pool or in a floating chlorine dispenser.

 

 

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Do you automatically adjust the “shrink factor” on your pool liners during the colder months so that I get a full cut liner with less stretch? If not, can I request a “winter cut”?

When we make a pool liner, we create a drawing that shows the dimensions of your swimming pool.  In the design process, we reduce certain dimensions to provide for just enough stretch so that the liner will fit without wrinkles, but also without stretching the vinyl too much.

Those of us who make the best liners and who are most confident in our ability to make great fitting liners use minimal shrink factors.  This is why good measurements are so critical and why you should always pay a pool professional to measure your swimming pool.  We do not adjust the length and width so that your liner will have the same perimeter as your pool.  Most of the time we only adjust the depth dimensions by a few inches to provide the proper amount of stretch.  We will also occasionally adjust the slope dimensions as needed.

This is how we make “full cut” liners that fit so well.  We do this year round.  In the old days, some manufacturers would make a “full cut” pool liner only in the cooler months.  In the summertime, they would shrink the dimensions more than normal, maybe even shrinking the length and width.  They knew that the hot summer sun would loosen up the vinyl, kind of like warm butter, and help it stretch into place.

Today, we make a “full cut” liner year-round, even on the hottest summer days.  No adjustments are necessary based on the season.

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.

Should I be able to see the liner seams in my vinyl pool liner?

We often hear pool owners question whether they should be able to see the seams in their liner.

The answer is yes.  Every liner has seams, at least every six feet, and they are more visible on some patterns than on others.  In the old days, when all patterns were on blue base film, you could not really see the seams since there was less ink coverage.  Today, when most all patterns are on white base film, the seams are more visible, but the less ink there is, the less noticeable they are.

We advise that you wait until the pool is filled before you worry about the seams.  While they are always there, they are much less noticeable under three feet of water.

The liner pictured below (pattern: Robertson) is a good example of visible liner seams on a properly manufactured liner.  The seams on the floor are barely visible.  The vertical seam is razor thin, perfectly straight and the tile is matched almost perfectly at the top.

seam-example3-north-wall-side-and-bottom-of-pool

 Bottom of pool (below):

seam-example1-bottom-of-pool

Pictured below is Morrison, one of our most popular patterns.  If you look closely, you can see two liner seams in the shallow end of the pool.  The Morrison pattern has one of the most visible liner seams out of all of our patterns.  That being said, you will notice that the seams are barely visible, especially if standing 10 feet away and if the pool is filled with water.

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In the picture below, you can see a seam across the bottom of an unfilled pool (pattern: McDowell).

mcdowell

Below, we present you with the McDowell pattern again in a pool completely filled with water.  From this viewpoint, it is impossible to notice any liner seams.

dsc03154

Pictured below are two more examples of highly visible liner seams on properly installed pool liners.

liners seams1

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